Brown County climate

Brown County Weather in September

NOAA 1991-2020 normals for Hiawatha 1 S, 2.9 km from Brown County

Average highs run from 83°F on September 1 to 75°F on September 30, and lows from 59°F to 49°F. Normal precipitation for the month is 3.22 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 Brown County, in °F, with the record for each date.20406080100120151015202530
  • Normal low
  • Normal high
  • Record high
  • Record low

September at a glance

Average high
79°F
Average low
54°F
Precipitation
3.22 in
Record high
104°FSep 3, 2011
Record low
31°FSep 23, 2012
Chance of a freeze
5%
Days of 90°F or more
4.0
Daylight
13 h 03 min to 11 h 48 min
Cloud cover
46%
Humidity
68%
Dew point
55°F
Wind
10.1 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 183°F59°F95°F 201046°F 200926%0%
Sep 282°F59°F98°F 201147°F 200925%0%
Sep 382°F59°F104°F 201150°F 201325%0%
Sep 482°F58°F95°F 201246°F 201025%0%
Sep 582°F58°F93°F 201246°F 201025%0%
Sep 681°F58°F91°F 201544°F 201125%0%
Sep 781°F57°F95°F 201543°F 201725%0%
Sep 881°F57°F97°F 201346°F 201225%0%
Sep 981°F56°F93°F 201339°F 200825%0%
Sep 1081°F56°F94°F 201340°F 200825%0%
Sep 1180°F56°F94°F 201346°F 200725%0%
Sep 1280°F55°F97°F 201346°F 200725%0%
Sep 1380°F55°F91°F 201134°F 201425%0%
Sep 1479°F55°F90°F 202245°F 200725%0%
Sep 1579°F54°F91°F 201737°F 200725%0%
Sep 1679°F54°F85°F 201539°F 200724%0%
Sep 1779°F54°F89°F 201547°F 201424%0%
Sep 1878°F53°F91°F 202238°F 201224%0%
Sep 1978°F53°F95°F 202239°F 201224%0%
Sep 2078°F52°F92°F 201644°F 200924%0%
Sep 2178°F52°F99°F 202243°F 201224%0%
Sep 2277°F52°F92°F 201743°F 201124%0%
Sep 2377°F51°F91°F 201731°F 201224%0%
Sep 2477°F51°F91°F 201731°F 201224%0%
Sep 2576°F51°F90°F 201742°F 202124%0%
Sep 2676°F50°F88°F 202040°F 200724%0%
Sep 2776°F50°F95°F 202140°F 200724%0%
Sep 2875°F49°F94°F 202141°F 200724%0%
Sep 2975°F49°F92°F 202137°F 202224%0%
Sep 3075°F49°F85°F 200737°F 202224%0%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Brown County, 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 6:50 AM, sunset 7:53 PM
September 30
sunrise 7:18 AM, sunset 7:06 PM

Every day of September: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00143634 (Hiawatha 1 S), public domain. Records: NOAA GHCN-Daily, station USC00143634, 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.