Phoenix · September
Run in the pre-dawn.
Average highs hit 99°F. September is the hottest stretch of the year. Heat builds fast after sunrise — the pre-dawn hour is the only reliably comfortable window.
Avg high / low
99° / 76°F
Humidity
35%
Rain days
6/mo
Wind
11 mph
What September feels like in Phoenix
Sunrise
06:12
Mid-month average
Sunset
18:33
Mid-month average
Time-of-day breakdown
Morning
Cool relative to the day's peak, but heat builds fast. By 10 AM you're already chasing comfort.
Midday
Heat peaks here. Skip unless you've got shade and pace tolerance.
Evening
Cools off after sunset but still warm. Good for easy efforts; avoid hard intervals if you're chasing pace.
What to wear running in Phoenix in September
The kit for September in Phoenix: light, breathable, and moisture-wicking — singlet or short-sleeve only.
September vs the surrounding months
vs August
-4° avg high
-2 rain days
Phoenix in August →
September
99°F avg high
6 rain days
Best: pre-dawn
vs October
+10° avg high
+3 rain days
Phoenix in October →
Frequently Asked Questions
What is the best time of day to run in Phoenix in September?+
Pre-dawn. Heat builds fast after sunrise — the pre-dawn hour is the only reliably comfortable window.
What's the average temperature in Phoenix in September?+
Average high 99°F, average low 76°F.
How does September compare to surrounding months in Phoenix?+
Compared to August (avg high 103°F), September is cooler. Compared to October (avg high 89°F), September is warmer.
Does it rain often in Phoenix in September?+
Expect about 6 measurable rain days in September, on average.