McHenry County Weather in August
Average highs run from 84°F on August 1 to 79°F on August 31, and lows from 64°F to 57°F. Normal precipitation for the month is 3.81 in over about 9 wet days.
August day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
August at a glance
- Average high
- 82°F
- Average low
- 61°F
- Precipitation
- 3.81 in
- Record high
- 102°FAug 2, 1988
- Record low
- 35°FAug 30, 1999
- Chance of a freeze
- 0%
- Days of 90°F or more
- 4.0
- Daylight
- 14 h 26 min to 13 h 11 min
- Cloud cover
- 52%
- Humidity
- 76%
- 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.
| Date | Normal high | Normal low | Record high | Record low | Chance wet | Chance of snow |
|---|---|---|---|---|---|---|
| Aug 1 | 84°F | 64°F | 95°F 2006 | 48°F 1990 | 29% | 0% |
| Aug 2 | 84°F | 64°F | 102°F 1988 | 49°F 2019 | 29% | 0% |
| Aug 3 | 84°F | 64°F | 99°F 1988 | 49°F 1976 | 29% | 0% |
| Aug 4 | 84°F | 64°F | 100°F 1988 | 46°F 1972 | 29% | 0% |
| Aug 5 | 84°F | 64°F | 98°F 1988 | 44°F 1972 | 29% | 0% |
| Aug 6 | 84°F | 64°F | 91°F 1965 | 45°F 1992 | 29% | 0% |
| Aug 7 | 84°F | 63°F | 95°F 1968 | 46°F 1990 | 29% | 0% |
| Aug 8 | 84°F | 63°F | 96°F 1988 | 45°F 1976 | 29% | 0% |
| Aug 9 | 84°F | 63°F | 96°F 1983 | 43°F 1964 | 29% | 0% |
| Aug 10 | 83°F | 63°F | 95°F 2005 | 48°F 1972 | 28% | 0% |
| Aug 11 | 83°F | 63°F | 94°F 1958 | 46°F 1967 | 28% | 0% |
| Aug 12 | 83°F | 63°F | 94°F 1988 | 42°F 1967 | 28% | 0% |
| Aug 13 | 83°F | 62°F | 94°F 1988 | 40°F 1967 | 28% | 0% |
| Aug 14 | 83°F | 62°F | 93°F 1965 | 40°F 1964 | 28% | 0% |
| Aug 15 | 82°F | 62°F | 94°F 1988 | 40°F 1964 | 28% | 0% |
| Aug 16 | 82°F | 62°F | 96°F 2000 | 40°F 1979 | 28% | 0% |
| Aug 17 | 82°F | 61°F | 101°F 1988 | 43°F 1979 | 28% | 0% |
| Aug 18 | 82°F | 61°F | 100°F 1988 | 42°F 1962 | 28% | 0% |
| Aug 19 | 82°F | 61°F | 96°F 1955 | 45°F 1953 | 28% | 0% |
| Aug 20 | 81°F | 61°F | 99°F 1955 | 44°F 1953 | 28% | 0% |
| Aug 21 | 81°F | 60°F | 100°F 1955 | 43°F 2004 | 27% | 0% |
| Aug 22 | 81°F | 60°F | 94°F 2003 | 43°F 2004 | 27% | 0% |
| Aug 23 | 81°F | 60°F | 94°F 1968 | 44°F 1952 | 27% | 0% |
| Aug 24 | 80°F | 59°F | 95°F 1962 | 45°F 1952 | 27% | 0% |
| Aug 25 | 80°F | 59°F | 94°F 2023 | 39°F 1958 | 27% | 0% |
| Aug 26 | 80°F | 59°F | 94°F 2003 | 41°F 1964 | 27% | 0% |
| Aug 27 | 80°F | 58°F | 96°F 1953 | 44°F 1968 | 27% | 0% |
| Aug 28 | 80°F | 58°F | 96°F 1973 | 40°F 1968 | 27% | 0% |
| Aug 29 | 79°F | 58°F | 95°F 1953 | 41°F 1965 | 27% | 0% |
| Aug 30 | 79°F | 57°F | 96°F 1984 | 35°F 1999 | 26% | 0% |
| Aug 31 | 79°F | 57°F | 96°F 1953 | 40°F 2009 | 26% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (CDT).
- August 1
- sunrise 5:47 AM, sunset 8:13 PM
- August 31
- sunrise 6:18 AM, sunset 7:29 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00112048 (Crystal Lake 4NW), public domain. Records: NOAA GHCN-Daily, station USC00471205, 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.