Keystone climate

Keystone Weather in September

NOAA 1991-2020 normals for Belle Plaine, 14.5 km from Keystone

Average highs run from 80°F on September 1 to 71°F on September 30, and lows from 57°F to 45°F. Normal precipitation for the month is 3.55 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 Keystone, in °F, with the record for each date.20406080100120151015202530
  • Normal low
  • Normal high
  • Record high
  • Record low

September at a glance

Average high
76°F
Average low
51°F
Precipitation
3.55 in
Record high
100°FSep 4, 1947
Record low
22°FSep 28, 1942
Chance of a freeze
18%
Days of 90°F or more
1.5
Daylight
13 h 07 min to 11 h 47 min
Cloud cover
49%
Humidity
71%
Dew point
53°F
Wind
9.4 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 180°F57°F98°F 195334°F 194926%0%
Sep 280°F56°F99°F 195340°F 194626%0%
Sep 380°F56°F99°F 194737°F 197426%0%
Sep 479°F56°F100°F 194736°F 197426%0%
Sep 579°F55°F97°F 202339°F 197426%0%
Sep 679°F55°F95°F 194736°F 195026%0%
Sep 779°F55°F97°F 198536°F 202526%0%
Sep 878°F54°F96°F 194735°F 202526%0%
Sep 978°F54°F100°F 195539°F 194925%0%
Sep 1078°F53°F99°F 201335°F 197625%0%
Sep 1178°F53°F97°F 201335°F 195525%0%
Sep 1277°F53°F94°F 195233°F 195525%0%
Sep 1377°F52°F88°F 195232°F 195325%0%
Sep 1477°F52°F95°F 202536°F 194925%0%
Sep 1576°F51°F95°F 195531°F 200725%0%
Sep 1676°F51°F93°F 195531°F 198425%0%
Sep 1776°F51°F93°F 195537°F 199925%0%
Sep 1875°F50°F94°F 194734°F 198125%0%
Sep 1975°F50°F98°F 194833°F 199125%0%
Sep 2075°F49°F91°F 202429°F 199125%0%
Sep 2174°F49°F97°F 202228°F 198225%0%
Sep 2274°F49°F90°F 201726°F 198225%0%
Sep 2373°F48°F91°F 201729°F 198325%0%
Sep 2473°F48°F91°F 201730°F 198925%0%
Sep 2573°F47°F89°F 201731°F 194225%0%
Sep 2672°F47°F88°F 201728°F 198425%0%
Sep 2772°F46°F89°F 195426°F 202226%0%
Sep 2871°F46°F100°F 195322°F 194226%0%
Sep 2971°F46°F96°F 195323°F 198426%0%
Sep 3071°F45°F92°F 195225°F 198426%0%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Keystone, in percent, and of at least 0.1 inch of snowfall.01020301102030
  • Chance of a wet day
  • Chance of snowfall

Sunrise and sunset

Times for 2026, local time (CDT).

September 1
sunrise 6:35 AM, sunset 7:42 PM
September 30
sunrise 7:05 AM, sunset 6:52 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00130600 (Belle Plaine), public domain. Records: NOAA GHCN-Daily, station USC00138568, 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.