September weather forecastPhoenix, AZ
September
Weather in September
The arrival of September in Phoenix marks the outset of milder temperatures and reduced humidity. The city starts to witness a notable drop in temperatures, signaling the retreat of the sweltering summer with a distinct autumn breeze. With average highs descending to 96.3°F (35.7°C), it's a welcome change from the burning summer months. As September progresses, the likelihood of rainfall diminishes, and the city slowly returns to drier conditions. The first hints of fall can be noticed, and Phoenix prepares to settle into a much more forgiving climate.Temperature
The transition to September results in a modest reduction in average high-temperature, moving from a fiery hot 102.6°F (39.2°C) in August to a still torrid 96.3°F (35.7°C). Throughout September, the nighttime temperature averages to a moderately hot 78.8°F (26°C).Humidity
The average relative humidity in September is 30%.Rainfall
In September, the rain falls for 4.7 days. Throughout September, 0.67" (17mm) of precipitation is accumulated. In Phoenix, during the entire year, the rain falls for 44.6 days and collects up to 5.04" (128mm) of precipitation.Snowfall
The only month with snowfall is September. The month with the most snowfall is September, when snow falls for 0.1 days and typically aggregates up to 0.04" (1mm) of snow.Daylight
The average length of the day in September is 12h and 22min.On the first day of the month, sunrise is at 6:02 am and sunset at 6:53 pm. On the last day of September, sunrise is at 6:22 am and sunset at 6:13 pm MST.
Sunshine
In September, the average sunshine is 9.7h.UV index
In Phoenix, the average daily maximum UV index in September is 7. A UV Index estimate of 6 to 7 represents a high threat to health from unsafe exposure to UV radiation for ordinary individuals.Note: An average UV index of 7 in September transforms into this advice:
Deter overexposure. Protecting against the sun's effects is essential. The Sun's UV radiation is most powerful between 10 a.m. and 4 p.m. To the extent possible, limit exposure to the direct sun during these hours. Enhance your sun protection with tightly woven, yet airy clothing. Foresee this! The reflection from snow can nearly double the intensity of UV radiation from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Phoenix, AZ
- Average high temperature in September: 96.3°F
The warmest month (with the highest average high temperature) is July (103.6°F).
The month with the lowest average high temperature is December (63°F).
- Average low temperature in September: 78.8°F
The month with the highest average low temperature is August (84.7°F).
The coldest month (with the lowest average low temperature) is January (47.5°F).
Average pressure in September
Phoenix, AZ
- Average pressure in September: 29.87"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.81"Hg).
Average wind speed in September
Phoenix, AZ
- Average wind speed in September: 5.2mph
The windiest month (with the highest average wind speed) is April (6.4mph).
The calmest month (with the lowest average wind speed) is December (4.3mph).
Average humidity in September
Phoenix, AZ
- Average humidity in September: 30%
The month with the highest relative humidity is December (43%).
The month with the lowest relative humidity is June (16%).
Average rainfall in September
Phoenix, AZ
- Average rainfall in September: 0.67"
The wettest month (with the highest rainfall) is July (0.75").
The driest months (with the least rainfall) are May and June (0.08").
Average rainfall days in September
Phoenix, AZ
- Average rainfall days in September: 4.7 days
The month with the highest number of rainy days is July (7.8 days).
The month with the least rainy days is June (0.8 days).
Average snowfall in September
Phoenix, AZ
- Average snowfall in September: 0.04"
The month with the highest snowfall is September (0.04").
The months with the least snowfall are January, February, March, April, May, June, July, August, October, November and December (0").
Average snowfall days in September
Phoenix, AZ
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is September (0.1 days).
The months with the least snowfall days are January, February, March, April, May, June, July, August, October, November and December (0 days).
Average daylight in September /
Average sunshine in September
Phoenix, AZ
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).
- Average sunshine in September: 9h and 42min
The month with the most sunshine is June (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 48min).
Average sunshine days in September
Phoenix, AZ
- Average sunshine days in September: 23.7 days
The month with the most sunshine days is May (29.2 days).
The month with the least sunshine days is July (21.1 days).
Average UV index in September
Phoenix, AZ
- Average UV index in September: 7
The months with the highest UV index are May, June, July and August (UV index 8).
The month with the lowest UV index is December (UV index 3).
Average cloud cover in September
Phoenix, AZ
- Average cloud cover in September: 10
The month with the most cloud cover is December (Cloud cover 21).
The month with the least cloud cover is June (Cloud cover 5).
Average visibility in September
Phoenix, AZ
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
