Johnson County climate

Johnson County Weather in August

NOAA 1991-2020 normals for Iowa City Muni AP, 5.7 km from Johnson County

Average highs run from 85°F on August 1 to 82°F on August 31, and lows from 66°F to 60°F. Normal precipitation for the month is 3.94 in over about 10 wet days.

August day by day

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

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

August at a glance

Average high
84°F
Average low
63°F
Precipitation
3.94 in
Record high
101°FAug 20, 2003
Record low
40°FAug 20, 1950
Chance of a freeze
0%
Days of 90°F or more
4.0
Daylight
14 h 23 min to 13 h 10 min
Cloud cover
50%
Humidity
71%
Dew point
62°F
Wind
7.8 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
Aug 185°F66°F96°F 201254°F 199732%0%
Aug 285°F66°F98°F 201153°F 195032%0%
Aug 385°F65°F99°F 200552°F 195032%0%
Aug 485°F65°F93°F 200853°F 201733%0%
Aug 585°F65°F94°F 201849°F 194833%0%
Aug 685°F65°F96°F 202248°F 194833%0%
Aug 785°F65°F95°F 201250°F 199733%0%
Aug 885°F65°F95°F 200550°F 199733%0%
Aug 985°F65°F100°F 200552°F 202433%0%
Aug 1085°F65°F93°F 200551°F 202433%0%
Aug 1185°F65°F92°F 199550°F 200433%0%
Aug 1284°F64°F94°F 199549°F 200433%0%
Aug 1384°F64°F93°F 199549°F 200433%0%
Aug 1484°F64°F90°F 200043°F 200433%0%
Aug 1584°F64°F93°F 200344°F 200433%0%
Aug 1684°F64°F96°F 200347°F 200433%0%
Aug 1784°F63°F92°F 200352°F 201233%0%
Aug 1884°F63°F95°F 200547°F 200233%0%
Aug 1984°F63°F94°F 200548°F 195033%0%
Aug 2083°F63°F101°F 200340°F 195033%0%
Aug 2183°F63°F93°F 199844°F 195033%0%
Aug 2283°F62°F93°F 202349°F 194933%0%
Aug 2383°F62°F100°F 202345°F 195233%0%
Aug 2483°F62°F100°F 202343°F 195233%0%
Aug 2583°F62°F98°F 200348°F 195233%0%
Aug 2683°F61°F98°F 200349°F 202533%0%
Aug 2783°F61°F97°F 201350°F 202533%0%
Aug 2882°F61°F96°F 201355°F 194933%0%
Aug 2982°F61°F96°F 194851°F 200433%0%
Aug 3082°F60°F101°F 201350°F 200933%0%
Aug 3182°F60°F98°F 200045°F 194933%0%

Chance of rain

The chance of at least 0.01 inch of precipitation on each date at Johnson 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).

August 1
sunrise 6:01 AM, sunset 8:24 PM
August 31
sunrise 6:31 AM, sunset 7:41 PM

Every day of August: sun and moon

Other months

Sources

Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USW00014937 (Iowa City Muni AP), public domain. Records: NOAA GHCN-Daily, station USW00014937, 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.