Rock County climate

Rock County Weather in September

NOAA 1991-2020 normals for Afton - Janesville Wwtp, 3.8 km from Rock County

Average highs run from 80°F on September 1 to 69°F on September 30, and lows from 56°F to 45°F. Normal precipitation for the month is 3.73 in over about 10 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 Rock County, in °F, with the record for each date.20406080100151015202530
  • Normal low
  • Normal high
  • Record high
  • Record low

September at a glance

Average high
75°F
Average low
51°F
Precipitation
3.73 in
Record high
96°FSep 2, 2000
Record low
28°FSep 23, 1995
Chance of a freeze
10%
Days of 90°F or more
1.5
Daylight
13 h 09 min to 11 h 46 min
Cloud cover
51%
Humidity
75%
Dew point
54°F
Wind
9.2 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°F56°F94°F 201240°F 200933%0%
Sep 279°F56°F96°F 200043°F 200933%0%
Sep 379°F56°F92°F 199943°F 198733%0%
Sep 479°F55°F94°F 202340°F 199733%0%
Sep 579°F55°F94°F 201238°F 198833%0%
Sep 679°F55°F95°F 199039°F 198833%0%
Sep 778°F54°F92°F 201641°F 202534%0%
Sep 878°F54°F91°F 200341°F 202434%0%
Sep 978°F54°F91°F 200241°F 199534%0%
Sep 1077°F53°F94°F 201342°F 199534%0%
Sep 1177°F53°F95°F 201337°F 199334%0%
Sep 1277°F53°F91°F 200539°F 199334%0%
Sep 1376°F52°F91°F 200538°F 201434%0%
Sep 1476°F52°F91°F 199837°F 201434%0%
Sep 1576°F51°F89°F 202434°F 200734%0%
Sep 1675°F51°F90°F 202435°F 200734%0%
Sep 1775°F51°F91°F 198838°F 199934%0%
Sep 1875°F50°F91°F 201839°F 199934%0%
Sep 1974°F50°F88°F 200736°F 201234%0%
Sep 2074°F49°F91°F 202133°F 199134%0%
Sep 2173°F49°F93°F 201732°F 199134%0%
Sep 2273°F49°F92°F 201733°F 198934%0%
Sep 2373°F48°F95°F 201728°F 199534%0%
Sep 2472°F48°F95°F 201729°F 199534%0%
Sep 2572°F47°F93°F 201733°F 199534%0%
Sep 2671°F47°F94°F 201732°F 198934%0%
Sep 2771°F46°F90°F 199829°F 199134%0%
Sep 2870°F46°F88°F 202130°F 199134%0%
Sep 2970°F46°F84°F 202530°F 199134%0%
Sep 3069°F45°F89°F 202529°F 199334%0%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Rock County, in percent, and of at least 0.1 inch of snowfall.0102030401102030
  • Chance of a wet day
  • Chance of snowfall

Sunrise and sunset

Times for 2026, local time (CDT).

September 1
sunrise 6:21 AM, sunset 7:30 PM
September 30
sunrise 6:53 AM, sunset 6:39 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00470045 (Afton - Janesville Wwtp), public domain. Records: NOAA GHCN-Daily, station USC00470045, 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.