Climate averages 1991–2020

Tempe weather
in September.

A very hot, fairly dry month: the 4th warmest and the 7th driest of the year.

Long-term climate patterns, not a forecast for a particular trip.

Average high 36.8°C Daytime mean, September
Average low 23.2°C Night-time mean, September
Rainfall 24 mm 3 days with ≥1 mm
Daylight 12 h Sunrise to sunset, per day
Every month in Tempe · average highYear overview

September is a very hot month in Tempe: daytime highs average 36.8°C and nights cool to about 23.2°C. By daytime temperature it is the 4th warmest of the 12 months.

Expect about 24 mm of rain on roughly 3 days, which makes September a fairly dry month (the 7th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 25 min on an average September day.

The nearest other city in this atlas is Mesa (8 km away). In September its highs average 36.6°C, about as warm as Tempe, with 26 mm of rain.

Among the 498 cities listed in the United States, Tempe ranks joint 7th of 498 for the warmest September highs and joint 129th of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; Tempe is 9.9°C warmer than that mean.

From September to October, average highs fall by 6.1°C to 30.7°C, and monthly rainfall falls from 24 mm to 20 mm.

The annual picture

September in context

30-year average
Average highAverage low°C
Average daily high and low temperatures by month The same values are available in the monthly table below. Lines show mean daily maxima and minima, not a forecast interval. 051015202530354045 JanFebMarAprMayJunJulAugSepOctNovDec

Monthly rainfall

Average total · mm
Average monthly rainfall totalsEach bar is a mean monthly total over 1991–2020. Full numbers are in the table. JanFebMarAprMayJunJulAugSepOctNovDec 500

Averages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated

Every month, side by side

Tempe climate table

1991–2020
Monthly climate averages for Tempe, 1991–2020
MonthAverage highHigh / lowAverage lowRainfall mm/monthRain days ≥1 mm/dayDaylight hours/dayDay­light h/day
January 18.6°C4.4°C4.4°C323.710.210 h
February 20.4°C6.1°C6.1°C384.111.011 h
March 24.5°C9.0°C9.0°C262.812.012 h
April 29.0°C13.0°C13.0°C8.01.313.013 h
May 34.1°C18.3°C18.3°C4.10.613.914 h
June 39.6°C23.7°C23.7°C1.80.414.314 h
July 40.5°C27.8°C27.8°C193.514.114 h
August 39.5°C27.3°C27.3°C294.413.413 h
September, selected 36.8°C23.2°C23.2°C243.112.412 h
October 30.7°C15.8°C15.8°C202.211.411 h
November 23.7°C9.1°C9.1°C182.210.510 h
December 17.8°C4.3°C4.3°C283.610.010 h

Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.

Compare places

September in nearby cities

Distance from Tempe

Read the numbers correctly

Climate, not a promise.

These patterns help compare months. They cannot tell you the weather on a specific day of your trip.

Sources, method and limits

How these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Tempe) is explained once on the Tempe year overview and on the Sources, method and limits page.

Phoenix and Scottsdale lie in the same rainfall cell, so their rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.