While the Western United States are occupied mostly by mountains and plateaus, with vast arid and desert areas, the central-eastern part is mostly flat or covered by hills and low mountains, and its climate is generally more humid and rainy. Given the vastness of the territory, climatic differences are remarkable here as well.
Clashes of air masses are large and frequent, making the climate unstable in most of the territory, and meteorological phenomena may be violent (storms, hail, blizzards, tornadoes). Air masses coming from Canada are cold and dry (but pick up moisture when passing over the Great Lakes), while those from the Gulf of Mexico are warm and moist.
We divided the territory into four bands, substantially parallel; within each of them the climate is fairly uniform, although the westernmost part, that of the Great Plains, experiences higher temperature variations, and is also less humid and rainy than the eastern part, especially in winter.

Index

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• 1- The far north - Duluth
• 2- The north - Fargo, Chicago
• 3- The central belt - Cincinnati, New York, Washington
• 4- The southern belt - Dallas, Atlanta
• 5- Gulf of Mexico and Florida - Houston, Orlando, Miami
• Hurricanes

1- The far north

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In the northernmost part (which includes the northernmost part of Montana, North Dakota, Minnesota, Wisconsin and Michigan, the north-east of the state of New York, and northern part of Vermont, New Hampshire and Maine), the climate is continental with long, cold, and snowy winters, and moderately warm summers. The average daily temperature in January is several degrees below freezing, from -15 °C (5 °F) to -5 °C (23 °F), while in July it doesn't reach 20 °C (68 °F). Summer is a fairly rainy season because of afternoon thunderstorms in the west, and also because of the weather disturbances that can affect the areas of the Great Lakes and the east. However, the sun frequently shines. During summer, intense heat waves can occur, with peaks above 35 °C (95 °F), but they only last a few days.

Duluth

Here are the average temperatures of Duluth (Minnesota).

In Duluth, precipitation amounts to 775 millimetres (30.5 inches) per year, with a minimum in winter, when there are frequent snowfalls, though generally not abundant, and a maximum in summer. Here is the average precipitation.

In Duluth, the sun does not shine often in winter, while in summer all in all it shines for a good number of hours.

Near Duluth, Lake Superior approaches the freezing point in winter (but on colder winters, a thick layer of ice forms), while in summer, although it warms up considerably, it remains very cool, if not cold, for swimming.

In this area, precipitation is fairly scarce in the western part, where it's inferior to 500 millimetres (20 inches) per year, mainly because of the relatively dry winter, while it's more abundant in the Great Lakes region and in the north-east. As a consequence, snowfalls (which typically occur from late October to mid-April) are relatively less abundant in the west, where they amount to about 70 cm (27.5 in) per year in North Dakota, while they are definitely abundant around the Great Lakes and in the north-east: typically they range from 150 to 250 cm (60 to 100 in), but can even surpass 3 metres (120 in) in the Upper Peninsula. In the area of the Great Lakes, winter snowfalls are more abundant along the coasts exposed to the north and west (because of a phenomenon called lake-effect snow, whereby cold winds, initially dry, pick up moisture above the lakes, and bring snowfall on the leeward shores). In Houghton, northern Michigan, on the shores of Lake Superior, 4 metres (13 feet) of snow fall per year; in L'Anse, a little more to the south and 500 metres (1,600 feet) above sea level, snowfall amounts to almost 6 metres (20 feet) per year!
In the northeast, Mount Washington, in New Hampshire, 1,917 metres (6,289 feet) high, is constantly affected by disturbances generated by clashes of warm and cold air masses, and receives no less than 7 metres (23 feet) of snow per year.



Being the climate of this area inhospitable, no large cities are found.

2- The north

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In this band (which in the southern part extends to the north of Nebraska, Iowa, Illinois, Indiana, Ohio, Pennsylvania, Connecticut and Massachusetts), the climate is continental: winter is still cold and snowy, but summer is warm or even hot, with averages of July equal to or higher than 20 °C (68 °F). During summer, thunderstorms can occur in the afternoon, though they are generally less intense and frequent than in the central and southern regions. Winter temperatures are very low: the average in January hovers between -15 °C and -3 °C (5 and 27 °F).
Here too, the western part, that of the Great Plains, is more arid than the central and eastern part.
During winter, cold air outbreaks from Canada are accompanied by furious gusts of blizzard, and the temperature can drop below -30 °C (-22 °F). Snowy landscapes and sub-freezing temperatures even during the day, are the norm for weeks.
Snowfall is more abundant in the Great Lakes area and in the east, where it ranges from 150 to 250 cm (60 to 100 in) per year, while it drops below 1 metre (3.3 feet) in the westernmost states (Montana, North and South Dakota).
During summer, there may be intense heat waves, with higher temperature but lower humidity in the west, where highs can exceed 40 °C (104 °F), and more sultry and uncomfortable heat in the Great Lakes and in the east; anyway, they generally last a few days.

Fargo

In Fargo, North Dakota, the average in January is -12.7 °C (9.1 °F), like in northern Sweden. The temperature drops below -18 °C (0 °F) for fifty days a year on average. Summer is warm: the average in July is 21.5 °C (70.5 °F), although the nights remain typically cool.

In Fargo, precipitation amounts to 570 mm (22.5 in) per year, with a minimum in winter, and a maximum in early summer due to afternoon thunderstorms. Snowfall amounts to 130 cm (50 in) per year. Here is the average precipitation.

Despite the thunderstorms, the sun in Fargo shines regularly in summer.

With an average January temperature of -9 °C (16 °F), Minneapolis, Minnesota, in winter is colder than Moscow, Russia. In a typical year, from November to April, 130 cm (50 in) of snow fall. In the worst periods, the temperature can plunge to -40 °C (-40 °F). On the other hand, summer is quite hot: the average in July is 23 °C (73 °F). Precipitation, about 770 mm (30 in), is scarcer in winter and more abundant in summer, when it occurs mainly in the form of thunderstorm.
Further south, in Des Moines (Iowa), the average temperature goes from -5.3 °C (22.5 °F) in January, to 24.5 °C (76 °F) in July. On average, 94 cm (37 in) of snow fall each year.

Chicago

On the coast of Lake Michigan, Chicago, known as the "Windy City", has a freezing winter, with outbreaks of cold air from the Canadian Arctic region, and humid and hot summers, with thunderstorms in the afternoon, and also with possible heat waves. The average in January is -4.5 °C (24 °F), but the temperature drops below -18 °C (0 °F) for an average of 6 nights per year. Snowfall amounts to about one metre (3.3 ft) per year. The daily average in July is 23.5 °C (74.5 °F). During summer, the temperature exceeds 32 °C (90 °F) for 21 days on average.

In Chicago, 940 mm (37 in) of rain or snow fall per year, with a relative minimum in winter and a summer maximum. Here is the average precipitation.

Near Chicago, Lake Michigan is very cold in winter, while in summer it's still cool, but becomes almost acceptable for swimming, at least in August, or for those who are not sensitive to cold.

The climate of cities such as Indianapolis (Indiana), Detroit (Michigan) and Cleveland (Ohio), is similar to that of Chicago.
The coast of the state of New York overlooking Lake Erie and Lake Ontario has a similar temperature, but it's particularly snowy on account of the aforementioned lake-effect snow. In Buffalo, nearly 2 metres (6.5 feet) of snow fall per year. The temperatures are similar to those of Chicago, but summer is a bit less hot because of the cooling effect of the lake, which here is more evident. The Niagara Falls, a few kilometres (or miles) from Buffalo, also belong to this climate zone.
Along the east coast, the average in Portland (Maine), goes from -5 °C (23 °F) in January, to 20.5 °C (69 °F) in July. Annual precipitation is abundant, and amounts to 1,200 mm (47 in), well distributed throughout the year (with a relative minimum in summer). Here, 160 cm (63 in) of snow fall per year.

3- The central belt

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In this band (which includes Kansas, north of Oklahoma, Arkansas and Tennessee, Missouri, the south of Illinois and Indiana, Kentucky, West Virginia, the south of Pennsylvania and New York, New Jersey, Delaware, Massachusetts, Connecticut, Rhode Island, Virginia, District of Columbia), the climate is continental, but is more forgiving in winter, while it becomes hot in summer. Winter is still cold, with an average in January ranging from -3 °C to 4 °C (26.5 to 39 °F); there can be waves of cold, but they alternate with mild periods. Summer is hot and sunny, especially in the western part, while it's a bit milder in the area of the Appalachian Mountains and along the east coast. Summer is a fairly rainy season, mainly because of afternoon thunderstorms, but in the central and eastern part, some weather fronts may also pass. In summer, heat waves can occur, sometimes intense, and unlike in the north of the country, they can be persistent.
(The north-western part of Texas, where lies Amarillo, is part of the highlands, of which we have dealt with in the page of the western United States.)

In this area, several large cities are found.

Kansas City is located in the Great Plains of the Midwest, near the geometric centre of the United States; here winter is cold, so that the average in January is -0.8 °C (30.6 °F); summer is definitely hot, in fact the average in July is 27.3 °C (81.1 °F), and muggy too. The amount of sunshine is great: 2,800 hours per year. The rainfall amounts to 1,000 mm (40 in) per year, and is most abundant in late spring and summer, when it often occurs in the form of thunderstorm. On average, 50 cm (20 in) of snow fall per year.
Further east, the climate of St. Louis (Missouri) and Cincinnati (Ohio) is similar to that of Kansas City.

Cincinnati

Here is average temperature in Cincinnati.

Here is the average precipitation in Cincinnati.

The amount of sunshine in Cincinnati is good, but not great, in the summer.

The Appalachian Mountains are very snowy in winter, at least on the north-western slopes: snowfall is abundant especially on the north-facing elevations of West Virginia, when it amounts to about 150 cm (60 in) per year, and is less abundant on those of Virginia, when it amounts to 50 cm (20 in) per year, while the altitude tempers a bit the summer heat in the cities located on hills.

On the east coast, the proximity to the sea makes the climate a bit more temperate, but it must be said that the prevailing currents come from inland, so the climate is still continental.

New York

New York, despite being on the coast and at a relatively low latitude, 40° north latitude, has a cold winter: the average in January is 0.5 °C (33 °F). Summer is hot and muggy, and the average in July is 24.5 °C (76 °F). The climate is perpetually unstable, therefore all kinds of weather may occur: clear or overcast, windy or calm, cold or warm, even within the same week. In the middle of winter, there can be mild days, about 15 °C (60 °F), but the northwest cold wind can rapidly lower the temperature, and maybe bring snowfall, in a few hours. On average, 68 cm (27 in) of snow fall per year, from December to March (but sometimes also in early April or late November). Precipitation is abundant: about 1,200 mm (47 in) each year, well distributed throughout the seasons; in summer they often take place in the form of thunderstorms. Despite this, the sun frequently shines. In winter, the city can experience snow storms and waves of frost, with night minima around -10/-15 °C (5/14 °F), while in summer, masses of warm and moist air from the Gulf of Mexico can make the heat uncomfortable.

In New York, the sea is very cold in winter, while in summer it is a bit cool, but all in all you can swim in July and August, and those who do not suffer from the cold can try to swim also in September.


Further to the north-east, Boston (Massachusetts), is a bit colder and snowier in winter: the average in January is -1.5 °C (29.5 °F), the annual amount of snow is 114 cm (45 in), and snow storms can be even worse than in New York. On the other hand, here summer is a little milder: the average in July is 23 °C (73 °F). The sea is colder, so that in spring sometimes fogs occur, while in summer the sea breezes are often effective in tempering the heat. Here too heat waves may occur in summer, and even here there are frequent thunderstorms in the afternoon, sometimes accompanied by hail.
In fact Boston is at the limit of this climate zone: moving further to the north or to the interior, we enter the previous area, the colder one of the north.

Washington

South of New York, Washington, the federal capital, is instead a bit warmer than the Big Apple: the average in January rises to 2.3 °C (36.1 °F), and in July to 26.6 °C (79 °F). Waves of frost and snow in winter are still possible, but they are a bit rarer: on average, 40 cm (16 in) of snow fall per year, but big snowfalls and winter storms occur only once every three or four years. Summer is hot and humid, with fewer breaks than in New York and Boston: here an annoying and sticky heat dominates, and it can last for weeks. Fortunately, here too there is a fair amount of afternoon thunderstorms, which can break the heat at least for a few hours.

4- The southern belt

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In this belt (which includes southern Oklahoma, north-central Texas, south-central Arkansas, southern Tennessee, and most of Mississippi, Alabama, Georgia and North Carolina), winter is mild, in fact the average temperature in January is between 4 °C and 9 °C (39 and 48 °F). However, short waves of frost are possible even at these latitudes. In the north of this band, still 15/20 cm (6/8 in) of snow fall per year, while in the south, the snowfall average drops to about a few centimetres per year, which means that sometimes it never snows for an entire winter (or maybe more than one).
Summer, is long, hot and muggy, tropical-like, with afternoon thunderstorms, sometimes intense, especially in the central and eastern part. Oklahoma and north-central Texas are often oppressively hot, with an annoying combination of moisture and high temperature: highs range between 34 °C and 36 °C (93/97 °F), but often reach 40 °C (104 °F) for weeks, and the humidity is quite high, at least in combination with these temperatures. Further east, temperatures are a bit lower, in fact highs are usually around 32/33 °C (90/91 °F), but relative humidity is even higher. After all, we are at the latitude of northern Africa, but south of this area, instead of the Sahara, there is the Gulf of Mexico, from which warm and moist air masses often arrive.
Rainfall drops below 1,000 mm (40 in) per year in the western area (Texas, Oklahoma), while it's quite abundant in the central-eastern part, where it reaches about 1,200/1,300 mm (47/51 in) per year. Spring is a very rainy season because of the conflict between air masses coming from the north, which are still cold, and subtropical air masses lying in the south. In spring, tornadoes may also occur.
At this latitude, the westernmost part of Texas belongs to the Chihuahuan Desert, of which we have dealt with in the page of the western United States.
Now, let's see in detail the climate of some cities.

Dallas

In Dallas, the average temperature goes from 7.7 °C (45.9 °F) in January to 30.2 °C (86.4 °F) in July. In winter, the weather is often mild, with highs about 15/20 °C (59/68 °F), but there are also sudden cold waves, usually of short duration, when the temperature can drop to a few degrees below freezing. The winter rains are not abundant, and snowfall is rare: on average, 6 cm (2.4 in) of snow fall each year. Summer is long and oppressive, very difficult to bear, with some afternoon thunderstorms. There are as many as 100 days in a year with maximum temperatures above 32 °C (90 °F). The weather is pleasant in spring and autumn, although strong thunderstorms and even tornadoes may sometimes occur in spring, and more rarely in autumn.

In Dallas, the annual precipitation amounts to 920 mm (36 in). Here is the average precipitation.

In Dallas the sun shines quite often in winter, while in summer it shines often, roughly 3/4 of the time.


In Memphis, Tennessee, the average temperature goes from 5 °C (41 °F) in January, to 28 °C (82 °F) in July. Here, too, winter is mild, but it's possible to experience some short and intense waves of frost, accompanied with snow; on average, 12 cm (4.7 in) of snow fall per year. Rainfall, much more abundant than in Dallas, amounts to 1,360 mm (53.5 in) per year, with a relative minimum between August and October. Thunderstorms are possible throughout the year; in summer they are generally short-lived, while in spring they can be intense, and accompanied with wind gusts.

Atlanta

In Atlanta, Georgia, the slightly higher altitude, about 300 metres (1,000 feet), temper a little the summer heat: the average temperature is between 6.5 °C (43.5 °F) in January and 26.8 °C (80 °F) in July.

The rains are abundant here as well, amounting to 1,260 mm (49.5 in) per year, and are well distributed throughout the year.

In Atlanta, the sun shines quite often because the rains are usually intense and short-lived, so they do not decrease the sunshine duration by much.

5- Gulf of Mexico and Florida

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In this region, which includes the area bordering the Gulf of Mexico, the climate is sub-tropical, and it's warm and humid for many months of the year; winter is very mild, since the averages in January are higher than 9 °C (48 °F). But even here, in spite of the southern location, sometimes cold spells in winter may occur, though quite rarely; the southern part of Florida is the most sheltered, and is almost always spared from the cold, to the point of having an almost tropical climate.
Here too, the western part is less humid: precipitation drops below 1,000 mm (40 in) only in south-western Texas, while from eastern Texas to the far east, this whole band is rainy and with plenty of thunderstorms.
The amount of sunshine is not exceptional, in fact in the long summer season, although the sun still prevails, clouds can form in the afternoon, and can cause thunderstorms, while some tropical low pressure systems can pass over the area as well.
In this belt, October, and sometimes November, experience a relative lull in precipitation, with calm and pleasant days (if it is not affected by the last hurricanes of the season).

In Austin and San Antonio (Texas), in winter the weather is usually very mild, but with possible short waves of cold or frost: however, the average in January is around 10 °C (50 °F), and in the rest of the year the temperature is similar to that of Dallas, with an equally very hot and humid summer, while tornadoes in spring are less frequent because of the greater proximity to the sea.

The south-western tip of Texas, from Corpus Christi to the Mexican border, has a semi-arid climate, therefore it's different from the rest of the area, which is very rainy. Here the wettest period is from May to October (with a break in July); the rainiest month is September.

Houston

Houston is located about 50 kilometres (30 miles) away from the sea (but Galveston Bay borders the southeastern districts of the city): here the average temperature goes from 12.5 °C (54 °F) in January, to 29 °C (84 °F) in July, when highs are around 33/34 °C (92/93 °F) and the humidity is high. It's no surprise that a city so uncomfortably hot, has been the first in the world to see a widespread distribution of air conditioners.

In Houston, rainfall amounts to 1,400 mm (54 in) per year, so it's fairly abundant, and well distributed throughout the year. Here is the average precipitation.

In Houston the sun shines quite often, but the frequent rains and the cloud banks that come from the sea limit the total to 2,580 hours per year.

Near Houston, the Gulf of Mexico is warm enough for swimming from May to November, and it gets very warm in the summer months. In winter, it is cool but not cold, since it doesn't drop below 19 °C (66 °F) in February.

In New Orleans, Louisiana, the summer temperatures are similar to those of Houston, but the omnipresence of water makes the heat even more sweltering. The rains are definitely abundant: up to 1,575 mm (62 in) per year.

In peninsular Florida, winter is even milder, and spring-like.

Orlando

In Orlando and Tampa, the January average is around 15/16 °C (59/61 °F). There's a tropical weather from mid-May to September, with heat, humidity and frequent thunderstorms. April and October are hot, but a little drier.
Here are the average temperatures in Orlando.

In Orlando, 1,300 mm (51 in) of rain fall per year, but already at this latitude you can notice the minimum in winter due to the less frequent weather fronts, and the definite maximum in summer due to thunderstorms. Here is the average rainfall.

In Orlando the sun shines for a good number of hours all year round.

However, it's the southern part of Florida, which is a true winter refuge for many American snowbirds.

Miami

In Miami, on the southern tip of the state and near the Tropic of Cancer, the January average is 20 °C (68 °F), therefore here there is no winter: the sun often shines, the air is pleasantly warm, and a nice breeze blows from the sea. Very different, however, is the climate in the long hot summer, which is still sunny, but rainy as well, with frequent thunderstorms, at times strong. The rainiest period goes from May to mid-October. The heat is sweltering, even though the sticky heat is partially reduced by the breeze. Winter is instead quite dry, however, there are still 5/6 days with rainfall per month.

In Miami, the sea is warm enough for swimming all year round, since the water temperature in winter is 24 °C (75 °F); in summer, the sea is very warm for many months.

Hurricanes

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The states on the Gulf of Mexico (Texas, Louisiana, Mississippi, Alabama, Florida) as well as the southern Atlantic states (Georgia, North and South Carolina) can be affected by tropical depressions and hurricanes, which occasionally can also affect other Atlantic coastal states. The areas most at risk are the coastal ones, however, hurricanes can also penetrate inland, even though they tend to weaken. The hurricane season runs from June to November, although they are most likely from August to October.

Another danger comes from tornadoes, large and intense whirlwinds, which are very rare in the western part of the United States (the states of the Pacific and the Rocky Mountains, see the page of the Western United States), and are typical of the central and eastern states we are dealing with here, except the northern portions of the states of the Great Lakes and of the northeast. However, tornadoes are more frequent in the south-central band (zones 3 and 4), except on the coast. They develop mainly along two lines: the "Tornado Alley", from South Dakota to northern Texas (north/south direction), and the "Dixie Alley", from Oklahoma to Ohio (south-west/north-east direction).
The months when they are most frequent are May and June, but they may also occur between February and April, especially in the south, while in summer they can occur in the northern part of the Great Plains.
In Florida, tornadoes are quite frequent, but they are generally less intense than on the mainland.


See also:
United States West
Alaska
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