Climate in St Louis (Missouri)

The climate of St. Louis is continental, with cold winters and hot summers, with quite frequent thunderstorms.
The city is located in the Midwest of the United States, in the far east of Missouri, beyond which lies Illinois. The two great rivers of the United States, Mississippi and Missouri, meet in St. Louis. The Mississippi marks the border with Illinois. Across the river (hence in Illinois) are other cities that fall within the St. Louis metropolitan area.
The average temperature of the coldest month (January) is of 0.1 °C (32.1 °F), that of the warmest month (July) is of 26.9 °C (80.4 °F).
Precipitation amounts to 1,060 millimeters (41.7 inches) per year. Spring is the rainiest season due to clash between air masses and of afternoon thunderstorms, which continue throughout the summer, although gradually less frequently.



The winter, from late November to early March, is cold, with an average temperature in January close to freezing. There are periods when it may be cold at night, but during the day the temperature gets quite mild, reaching or exceeding 15 °C (59 °F). Sometimes it can reach 20 °C (68 °F) even in the middle of winter.
However, the city is exposed to intense cold spells, as is typical of the Midwest. On the coldest nights of the year, the temperature typically drops to around -18 °C (0 ° F). In recent decades, the cold record is -28 °C (-18.5 °F), recorded in January 1985.
On average, 42 cm (16.5 in) of snow fall per year. Therefore, snowfalls are not as abundant as in the Great Lakes region or on the east coast of the United States.

The summer, from June to August, is hot and quite sunny, although thunderstorms can break out in the afternoon.
St. Louis is a particularly hot city. There are hot and muggy periods, sometimes of long duration, which can also occur in early September.
Generally, the temperature reaches 37/38 °C (98/100 °F) on the hottest days of the year, although the record in recent times is 42.2 °C (108 °F), recorded at the end of June 2012. In July 2012, the average maximum temperature was of 38.1 °C (100.6 °F).

Spring and autumn, from mid-March to May and from September to mid-November, are contrasted seasons, with fairly frequent rains and sudden changes in temperature. Spring is rainier and more unstable than autumn. However, there are also stable and pleasant periods.
St. Louis is located east of the heart of Tornado Alley, and is one of the metropolitan areas most affected by this phenomenon. Tornadoes are are more likely in spring, but sometimes can also occur in autumn.

On average, there are around 2,595 sunshine hours per year. Therefore, the city is sunny. If we exclude the months of November and December, the sun shines for more than half the time all year round.
Occasionally, in spring, but especially in summer, the metropolitan area of St. Louis can be affected by floods of the Mississippi and Missouri. In 1993, during a historic flood, parts of the metropolitan area were flooded for months, with a peak in early August. The center of St. Louis, on the other hand, was saved thanks to the protections built after previous floods.
Even the smaller Meramec River is prone to flooding, as happened in December 2015 and May 2017.

Best Time

To visit St. Louis you can choose spring and autumn, and in particular the periods from mid-April to mid-May and from mid-September to mid-October. Autumn is probably the best season, being drier and with less temperature changes. But in spring the days are longer.

St Louis - Climate data

In St Louis, the average temperature of the coldest month (January) is of 0.1 °C (32.1 °F), that of the warmest month (July) is of 26.9 °C (80.3 °F). Here are the average temperatures.
Precipitation amounts to 1060 millimeters (41.7 inches) per year: it is therefore quite abundant. It ranges from 55 mm (2.2 in) in the driest month (February) to 120 mm (4.7 in) in the wettest ones (April, May) Here is the average precipitation.
There are on average around 2595 sunshine hours per year. Here are the average hours of sunshine per day.

St Louis - Weather by month

Based on the period 1991-2020

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January, the coldest month of the year, is generally a cold month. The average temperature is of 0.1 °C (32 °F), with a minimum of -4.6 °C (23.8 °F) and a maximum of 4.7 °C (40.4 °F).
On the coldest nights of the month, the temperature usually drops to around -15.5 °C (4.5 °F). However, it dropped to -22.3 °C (-8.1 °F) in January 1994.
On the warmest days of the month, the temperature usually reaches around 18.5 °C (65.5 °F). However, it reached 23.9 °C (75 °F) in January 2002.
Precipitation amounts to 65 mm (2.6 in), distributed over 9 days.
The day lasts on average 9 hours and 50 minutes.
There are on average 5 hours of sunshine per day. So, the sun shines 53% of the time.
The average humidity is 69%.
The average wind speed is 16 kph (10 mph).

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February is generally a cold month. The average temperature is of 2.6 °C (37 °F), with a minimum of -2.4 °C (27.6 °F) and a maximum of 7.7 °C (45.8 °F).
On the coldest nights of the month, the temperature usually drops to around -12.5 °C (9.5 °F). However, it dropped to -24.5 °C (-12.1 °F) in February 1996.
On the warmest days of the month, the temperature usually reaches around 21.5 °C (71 °F). However, it reached 27 °C (80.6 °F) in February 2000.
Precipitation amounts to 55 mm (2.2 in), distributed over 9 days.
The day lasts on average 10 hours and 50 minutes.
There are on average 5.5 hours of sunshine per day. So, the sun shines 52% of the time.
The average humidity is 65%.
The average wind speed is 16 kph (10 mph).

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March is generally a quite mild month. The average temperature is of 8.1 °C (47 °F), with a minimum of 2.6 °C (36.7 °F) and a maximum of 13.7 °C (56.6 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around -8 °C (18 °F). However, it dropped to -16.7 °C (1.9 °F) in March 2019.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 26.5 °C (79.5 °F). However, it reached 30.6 °C (87.1 °F) in March 1991.
Precipitation amounts to 90 mm (3.5 in), distributed over 11 days.
The day lasts on average 12 hours and 0 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 53% of the time.
The average humidity is 61%.
The average wind speed is 17 kph (10 mph).

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April is generally a mild month. The average temperature is of 14.2 °C (57 °F), with a minimum of 8.3 °C (47 °F) and a maximum of 20 °C (68 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 0 °C (32 °F). However, it dropped to -5 °C (23 °F) in April 2007.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 30 °C (86.5 °F). However, it reached 33.9 °C (93 °F) in April 2002.
Precipitation amounts to 120 mm (4.7 in), distributed over 12 days.
The day lasts on average 13 hours and 20 minutes.
There are on average 7.5 hours of sunshine per day. So, the sun shines 56% of the time.
The average humidity is 59%.
The average wind speed is 17 kph (10 mph).

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May is generally a warm month. The average temperature is of 19.7 °C (68 °F), with a minimum of 14.4 °C (57.9 °F) and a maximum of 25.1 °C (77.1 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 6.5 °C (43.5 °F). However, it dropped to 3.3 °C (37.9 °F) in May 1996.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 32.5 °C (90.5 °F). However, it reached 35.6 °C (96.1 °F) in May 2018.
Precipitation amounts to 120 mm (4.7 in), distributed over 13 days.
The day lasts on average 14 hours and 20 minutes. So the days are long.
There are on average 8.5 hours of sunshine per day. So, the sun shines 60% of the time.
The average humidity is 63%.
The average wind speed is 14 kph (9 mph).

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June is generally a warm to hot month. The average temperature is of 24.8 °C (77 °F), with a minimum of 19.6 °C (67.2 °F) and a maximum of 29.9 °C (85.9 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 13 °C (55.5 °F). However, it dropped to 8.9 °C (48 °F) in June 1993.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 35 °C (95.5 °F). However, it reached 42.2 °C (108 °F) in June 2012.
Precipitation amounts to 115 mm (4.5 in), distributed over 10 days.
The day lasts on average 14 hours and 50 minutes. So the days are long. June 21, the summer solstice, is the longest day of the year in the Northern Hemisphere.
There are on average 9.5 hours of sunshine per day. So, the sun shines 66% of the time.
The average humidity is 64%.
The average wind speed is 13 kph (8 mph).

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July, the hottest month of the year, is generally a warm to hot month. The average temperature is of 26.9 °C (80 °F), with a minimum of 21.7 °C (71.1 °F) and a maximum of 32 °C (89.6 °F).
On the coldest nights of the month, the temperature usually drops to around 16.5 °C (61.5 °F). However, it dropped to 13 °C (55.4 °F) in July 1997.
On the warmest days of the month, the temperature usually reaches around 37.5 °C (99 °F). However, it reached 42.2 °C (108 °F) in July 2012.
Precipitation amounts to 100 mm (3.9 in), distributed over 9 days.
The day lasts on average 14 hours and 30 minutes. So the days are long.
There are on average 10 hours of sunshine per day. So, the sun shines 69% of the time.
The average humidity is 64%.
The average wind speed is 12 kph (8 mph).

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August is generally a warm to hot month. The average temperature is of 26 °C (79 °F), with a minimum of 20.7 °C (69.3 °F) and a maximum of 31.3 °C (88.3 °F).
On the coldest nights of the month, the temperature usually drops to around 15.5 °C (60 °F). However, it dropped to 10.6 °C (51.1 °F) in August 1992.
On the warmest days of the month, the temperature usually reaches around 37.5 °C (99.5 °F). However, it reached 41 °C (105.8 °F) in August 2007.
Precipitation amounts to 85 mm (3.3 in), distributed over 8 days.
The day lasts on average 13 hours and 35 minutes.
There are on average 8.5 hours of sunshine per day. So, the sun shines 64% of the time.
The average humidity is 66%.
The average wind speed is 11 kph (7 mph).

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September is generally a warm month. The average temperature is of 21.7 °C (71 °F), with a minimum of 16.1 °C (60.9 °F) and a maximum of 27.3 °C (81.1 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 8.5 °C (47 °F). However, it dropped to 4.4 °C (39.9 °F) in September 1995.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 34 °C (93.5 °F). However, it reached 40 °C (104 °F) in September 2011.
Precipitation amounts to 75 mm (3 in), distributed over 7 days.
The day lasts on average 12 hours and 25 minutes.
There are on average 8 hours of sunshine per day. So, the sun shines 63% of the time.
The average humidity is 64%.
The average wind speed is 12 kph (7 mph).

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October is generally a very mild month. The average temperature is of 15.1 °C (59 °F), with a minimum of 9.5 °C (49.1 °F) and a maximum of 20.7 °C (69.2 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 1 °C (34 °F). However, it dropped to -2 °C (28.4 °F) in October 2006.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 30.5 °C (87 °F). However, it reached 34.4 °C (93.9 °F) in October 2006.
Precipitation amounts to 80 mm (3.1 in), distributed over 8 days.
The day lasts on average 11 hours and 5 minutes.
There are on average 6.5 hours of sunshine per day. So, the sun shines 61% of the time.
The average humidity is 63%.
The average wind speed is 14 kph (8 mph).

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November is generally a quite mild month. The average temperature is of 8 °C (46 °F), with a minimum of 3 °C (37.4 °F) and a maximum of 13.1 °C (55.5 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around -5.5 °C (22 °F). However, it dropped to -13.3 °C (8.1 °F) in November 1991.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 24 °C (75.5 °F). However, it reached 29.4 °C (84.9 °F) in November 2016.
Precipitation amounts to 85 mm (3.3 in), distributed over 9 days.
The day lasts on average 10 hours and 5 minutes.
There are on average 4.5 hours of sunshine per day. So, the sun shines 47% of the time.
The average humidity is 65%.
The average wind speed is 15 kph (9 mph).

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December is generally a cold month. The average temperature is of 2.5 °C (36 °F), with a minimum of -1.9 °C (28.5 °F) and a maximum of 6.9 °C (44.5 °F).
On the coldest nights of the month, the temperature usually drops to around -11.5 °C (11 °F). However, it dropped to -17 °C (1.4 °F) in December 2000.
On the warmest days of the month, the temperature usually reaches around 19.5 °C (67 °F). However, it reached 23.9 °C (75 °F) in December 2012.
Precipitation amounts to 65 mm (2.6 in), distributed over 9 days.
The day lasts on average 9 hours and 30 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
There are on average 4 hours of sunshine per day. So, the sun shines 44% of the time.
The average humidity is 69%.
The average wind speed is 15 kph (9 mph).