Climate - Phoenix (Arizona)

In Phoenix, the capital and the largest city of Arizona, and in the nearby town of Scottsdale, the climate is subtropical desert, very mild in winter and very hot in summer. The city is located at the 33rd parallel, 350 meters (1,150 feet) above sea level, and 250 km (155 miles) away from the Gulf of California, from where humid air masses can arrive in summer, which can bring some rain: we are in fact in the area of the Sonoran Desert, which is affected by the North American monsoon.
The average temperature of the coldest month (December) is of 13.2 °C (55.8 °F), that of the warmest month (July) is of 35.3 °C (95.5 °F). Here are the average temperatures.

In the United States, Phoenix is renowned for being a very hot city: in fact, it is the hottest of the big American cities. In one year, there are 173 days with more than 32 °C (89.5 °F), but above all, the temperatures can exceed 40 °C (104 °F) with a certain ease from May to September, and practically every year, 45 °C (113 °F) are exceeded on the hottest days. In June 1990, 50 °C (122 °F) were reached.
Moreover, while in June it's still dry, by July the humidity increases slightly, aggravating the sensation of heat. In fact, the average humidity goes from 16% in June, to 27% in July, to 32% in August.
Although winter is generally pleasantly mild, it can sometimes get a little cold, and there can be days with lows around freezing, or even slightly below, and highs of around 10 °C (50 °F).
In recent decades, the record is -3.5 °C (25.5 °F), recorded in December 1978. More recently, the temperature dropped to -3 °C (26.5 °F) in December 1990 and to -1.5 °C (29 °F) in January 2013.
Snow in Phoenix is very rare, although light snowfall is observed occasionally, typically without accumulation.
A bit of wind can blow all year round, but especially in spring, when clashes between air masses are more frequent, and still more in summer, when even sandstorms can occur.



Precipitation is definitely scarce, since it amounts to just 185 millimeters (7.2 inches) per year. The wettest periods are December-March, when disturbances may pass, and July-August, when, as mentioned, humid air can come from the Gulf of California and can trigger thunderstorms. The driest period is from April to June, when it rains very rarely. Here is the average rainfall.

The amount of sunshine in Phoenix is excellent all year round: the sky is almost always clear, and with 3,870 sunshine hours per year, it is one of the sunniest cities in the world. The sunniest period is the driest, from April to June, when the sun shines 90% of the time or more. Here is the average of the sunshine hours per day.

When to go

The best time to visit Phoenix is from November to March. Winter, from December to February, is generally a mild and sunny season, although it can sometimes rain, or it can get a bit cold (especially in December and January). You can therefore choose the months of March and November.

Phoenix - Weather by month

Based on the period 1991-2020

---

In January, the weather in Phoenix is usually mild. The average temperature is of 13.8 °C (57 °F), with a minimum of 7.8 °C (46 °F) and a maximum of 19.8 °C (67.6 °F).
On the coldest nights of the month, the temperature usually drops to around 2 °C (36 °F). However, it dropped to -2 °C (28.4 °F) in January 2007.
On the warmest days of the month, the temperature usually reaches around 25.5 °C (78 °F). However, it reached 30 °C (86 °F) in January 2003.
Precipitation amounts to 20 mm (0.8 in), distributed over 4 days.
The day lasts on average 10 hours and 10 minutes.
There are on average 8.5 hours of sunshine per day. So, the sun shines 81% of the time.
The average humidity is 43%.
The average wind speed is 8 kph (5 mph).

---

In February, the weather in Phoenix is usually very mild. The average temperature is of 15.5 °C (60 °F), with a minimum of 9.4 °C (49 °F) and a maximum of 21.6 °C (70.8 °F).
On the coldest nights of the month, the temperature usually drops to around 4.5 °C (39.5 °F). However, it dropped to -1.1 °C (30 °F) in February 2011.
On the warmest days of the month, the temperature usually reaches around 28 °C (82 °F). However, it reached 32.2 °C (90 °F) in February 2016.
Precipitation amounts to 20 mm (0.8 in), distributed over 4 days.
The day lasts on average 11 hours and 0 minutes.
There are on average 9 hours of sunshine per day. So, the sun shines 84% of the time.
The average humidity is 40%.
The average wind speed is 9 kph (6 mph).

---

In March, the weather in Phoenix is usually warm. However, there are remarkable differences between night and day. The average temperature is of 19.1 °C (66 °F), with a minimum of 12.5 °C (54.5 °F) and a maximum of 25.6 °C (78.1 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 6.5 °C (44 °F). However, it dropped to 3.3 °C (37.9 °F) in March 2002.
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 37.2 °C (99 °F) in March 2007.
Precipitation amounts to 20 mm (0.8 in), distributed over 3 days.
The day lasts on average 12 hours and 0 minutes.
There are on average 10.5 hours of sunshine per day. So, the sun shines 86% of the time.
The average humidity is 33%. Hence, the air is normally dry.
The average wind speed is 10 kph (6 mph).

---

In April, the weather in Phoenix is usually warm to hot. However, there are remarkable differences between night and day. The average temperature is of 22.9 °C (73 °F), with a minimum of 16 °C (60.8 °F) and a maximum of 29.7 °C (85.5 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 10 °C (50 °F). However, it dropped to 4 °C (39.2 °F) in April 1999.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 37 °C (99 °F). However, it reached 40.6 °C (105.1 °F) in April 1992.
Precipitation amounts to only 5 mm (0.2 in), distributed over 2 days.
The day lasts on average 13 hours and 5 minutes.
There are on average 12 hours of sunshine per day. So, the sun shines 90% of the time.
The average humidity is 23%. Hence, the air is normally dry.
The average wind speed is 12 kph (7 mph).

---

In May, the weather in Phoenix is usually very hot. However, there are remarkable differences between night and day. The average temperature is of 27.8 °C (82 °F), with a minimum of 20.8 °C (69.5 °F) and a maximum of 34.7 °C (94.5 °F).
On the coldest nights, which normally occur at the beginning of the month, the temperature usually drops to around 14.5 °C (58 °F). However, it dropped to 10 °C (50 °F) in May 1995.
On the warmest days, which normally occur at the end of the month, the temperature usually reaches around 41 °C (105.5 °F). However, it reached 44.4 °C (111.9 °F) in May 2020.
Precipitation amounts to only 5 mm (0.2 in), and all occurs in one day.
The day lasts on average 13 hours and 55 minutes.
There are on average 13 hours of sunshine per day. So, the sun shines 93% of the time.
The average humidity is 19%. Hence, the air is normally dry.
The average wind speed is 12 kph (7 mph).

---

In June, the weather in Phoenix is usually scorchingly hot. However, there are remarkable differences between night and day. The average temperature is of 33 °C (91 °F), with a minimum of 25.9 °C (78.6 °F) and a maximum of 40.1 °C (104.2 °F).
On the coldest nights, the temperature usually drops to around 20.5 °C (69 °F). However, it dropped to 15.6 °C (60.1 °F) in June 1993.
On the warmest days, the temperature usually reaches around 45 °C (112.5 °F). However, it reached 48.3 °C (118.9 °F) in June 2013.
Precipitation amounts to only 0 mm (0 in), so on average it never rains in the whole month.
The day lasts on average 14 hours and 20 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 13.5 hours of sunshine per day. So, the sun shines 95% of the time.
The average humidity is 16%. Hence, the air is normally dry.
The average wind speed is 11 kph (7 mph).

---

In July, the warmest month of the year, the weather in Phoenix is usually scorchingly hot. The average temperature is of 35.3 °C (96 °F), with a minimum of 29.2 °C (84.5 °F) and a maximum of 41.4 °C (106.5 °F).
On the coldest nights of the month, the temperature usually drops to around 23.5 °C (74.5 °F). However, it dropped to 21 °C (69.8 °F) in July 1999.
On the warmest days of the month, the temperature usually reaches around 46 °C (114.5 °F). However, it reached 49.4 °C (120.9 °F) in July 1995.
Precipitation amounts to 25 mm (1 in), distributed over 4 days.
The day lasts on average 14 hours and 5 minutes. So the days are long.
There are on average 12 hours of sunshine per day. So, the sun shines 87% of the time.
The average humidity is 27%. Hence, the air is normally dry.
The average wind speed is 12 kph (7 mph).

---

In August, the weather in Phoenix is usually scorchingly hot. The average temperature is of 34.6 °C (94 °F), with a minimum of 28.7 °C (83.6 °F) and a maximum of 40.6 °C (105.1 °F).
On the coldest nights of the month, the temperature usually drops to around 23.5 °C (74 °F). However, it dropped to 18 °C (64.4 °F) in August 2008.
On the warmest days of the month, the temperature usually reaches around 45 °C (113 °F). However, it reached 47.2 °C (117 °F) in August 2011.
Precipitation amounts to 25 mm (1 in), distributed over 5 days.
The day lasts on average 13 hours and 20 minutes.
There are on average 11.5 hours of sunshine per day. So, the sun shines 87% of the time.
The average humidity is 32%. Hence, the air is normally dry.
The average wind speed is 11 kph (7 mph).

---

In September, the weather in Phoenix is usually very hot. The average temperature is of 31.8 °C (89 °F), with a minimum of 25.6 °C (78.1 °F) and a maximum of 38 °C (100.4 °F).
On the coldest nights, the temperature usually drops to around 20 °C (68.5 °F). However, it dropped to 16.7 °C (62.1 °F) in September 2016.
On the warmest days, the temperature usually reaches around 43 °C (109 °F). However, it reached 45.6 °C (114.1 °F) in September 2020.
Precipitation amounts to 15 mm (0.6 in), distributed over 2 days.
The day lasts on average 12 hours and 20 minutes.
There are on average 11 hours of sunshine per day. So, the sun shines 89% of the time.
The average humidity is 30%. Hence, the air is normally dry.
The average wind speed is 10 kph (6 mph).

---

In October, the weather in Phoenix is usually warm to hot. However, there are remarkable differences between night and day. The average temperature is of 25.2 °C (77 °F), with a minimum of 18.7 °C (65.6 °F) and a maximum of 31.8 °C (89.2 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 12 °C (54 °F). However, it dropped to 6.1 °C (43 °F) in October 2019.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 38 °C (100.5 °F). However, it reached 41.1 °C (106 °F) in October 2015.
Precipitation amounts to 15 mm (0.6 in), distributed over 2 days.
The day lasts on average 11 hours and 20 minutes.
There are on average 10 hours of sunshine per day. So, the sun shines 88% of the time.
The average humidity is 29%. Hence, the air is normally dry.
The average wind speed is 9 kph (6 mph).

---

In November, the weather in Phoenix is usually warm. The average temperature is of 18.4 °C (65 °F), with a minimum of 12.1 °C (53.7 °F) and a maximum of 24.7 °C (76.5 °F).
On the coldest nights, which normally occur at the end of the month, the temperature usually drops to around 5.5 °C (42 °F). However, it dropped to 1.7 °C (35.1 °F) in November 1994.
On the warmest days, which normally occur at the beginning of the month, the temperature usually reaches around 31.5 °C (89 °F). However, it reached 36.7 °C (98.1 °F) in November 2020.
Precipitation amounts to 15 mm (0.6 in), distributed over 2 days.
The day lasts on average 10 hours and 25 minutes.
There are on average 8.5 hours of sunshine per day. So, the sun shines 82% of the time.
The average humidity is 35%. Hence, the air is normally dry.
The average wind speed is 8 kph (5 mph).

---

In December, the coldest month of the year, the weather in Phoenix is usually mild. The average temperature is of 13.2 °C (56 °F), with a minimum of 7.4 °C (45.3 °F) and a maximum of 19 °C (66.2 °F).
On the coldest nights of the month, the temperature usually drops to around 2 °C (35.5 °F). However, it dropped to 0 °C (32 °F) in December 2003.
On the warmest days of the month, the temperature usually reaches around 25.5 °C (78 °F). However, it reached 28.9 °C (84 °F) in December 2017.
Precipitation amounts to 20 mm (0.8 in), distributed over 4 days.
The day lasts on average 10 hours and 0 minutes. December 21, the winter solstice, is the shortest day of the year in the Northern Hemisphere.
There are on average 8 hours of sunshine per day. So, the sun shines 79% of the time.
The average humidity is 44%.
The average wind speed is 8 kph (5 mph).