Affton climate

Affton Weather in September

NOAA 1991-2020 normals for Cahokia, 12.2 km from Affton

Average highs run from 85°F on September 1 to 76°F on September 30, and lows from 64°F to 53°F. Normal precipitation for the month is 3.35 in over about 7 wet days.

September day by day

The normal high and low for each date, and the record, in °F.

Normal daily high and low temperature at Affton, in °F, with the record for each date.20406080100120151015202530
  • Normal low
  • Normal high
  • Record high
  • Record low

September at a glance

Average high
80°F
Average low
59°F
Precipitation
3.35 in
Record high
102°FSep 1, 2011
Record low
35°FSep 25, 2001
Chance of a freeze
1%
Days of 90°F or more
3.8
Daylight
13 h 00 min to 11 h 50 min
Cloud cover
46%
Humidity
68%
Dew point
56°F
Wind
5.1 mph

Every day of the month

A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.

DateNormal highNormal lowRecord highRecord lowChance wetChance of snow
Sep 185°F64°F102°F 201145°F 200923%0%
Sep 285°F64°F101°F 201146°F 201723%0%
Sep 384°F63°F100°F 201150°F 200923%0%
Sep 484°F63°F100°F 202647°F 199723%0%
Sep 584°F63°F102°F 202644°F 199723%0%
Sep 683°F62°F96°F 199849°F 200323%0%
Sep 783°F62°F96°F 200244°F 201723%0%
Sep 883°F62°F95°F 200242°F 202423%0%
Sep 983°F61°F97°F 201343°F 202424%0%
Sep 1082°F61°F98°F 201345°F 202424%0%
Sep 1182°F61°F98°F 201347°F 201724%0%
Sep 1282°F60°F94°F 202547°F 199724%0%
Sep 1381°F60°F96°F 202546°F 201424%0%
Sep 1481°F60°F97°F 202542°F 201424%0%
Sep 1581°F59°F100°F 202643°F 200724%0%
Sep 1680°F59°F95°F 201942°F 200024%0%
Sep 1780°F58°F98°F 202642°F 199924%0%
Sep 1880°F58°F95°F 202544°F 199924%0%
Sep 1979°F57°F96°F 202242°F 201224%0%
Sep 2079°F57°F99°F 201738°F 200624%0%
Sep 2179°F57°F97°F 202242°F 200024%0%
Sep 2278°F56°F98°F 201737°F 199924%0%
Sep 2378°F56°F95°F 201738°F 201224%0%
Sep 2478°F55°F95°F 201738°F 201224%0%
Sep 2577°F55°F95°F 201735°F 200124%0%
Sep 2677°F54°F93°F 201735°F 200024%0%
Sep 2777°F54°F92°F 199840°F 200024%0%
Sep 2876°F53°F90°F 202139°F 202224%0%
Sep 2976°F53°F92°F 201938°F 200324%0%
Sep 3076°F53°F92°F 201936°F 199924%0%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Affton, in percent, and of at least 0.1 inch of snowfall.05101520251102030
  • Chance of a wet day
  • Chance of snowfall

Sunrise and sunset

Times for 2026, local time (CDT).

September 1
sunrise 6:31 AM, sunset 7:31 PM
September 30
sunrise 6:56 AM, sunset 6:46 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00111160 (Cahokia), public domain. Records: NOAA GHCN-Daily, station USW00003960, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.