McHenry County Weather in May
Average highs run from 65°F on May 1 to 77°F on May 31, and lows from 41°F to 55°F. Normal precipitation for the month is 4.98 in over about 12 wet days.
May day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
May at a glance
- Average high
- 71°F
- Average low
- 48°F
- Precipitation
- 4.98 in
- Record high
- 94°FMay 29, 1991
- Record low
- 22°FMay 10, 1966
- Chance of a freeze
- 32%
- Days of 90°F or more
- 2.1
- Daylight
- 14 h 05 min to 15 h 03 min
- Cloud cover
- 66%
- Humidity
- 77%
- Dew point
- 50°F
- Wind
- 10.7 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 |
|---|---|---|---|---|---|---|
| May 1 | 65°F | 41°F | 85°F 1962 | 23°F 1984 | 39% | 1% |
| May 2 | 65°F | 42°F | 88°F 1952 | 25°F 1994 | 39% | 1% |
| May 3 | 66°F | 42°F | 88°F 1959 | 25°F 2004 | 39% | 1% |
| May 4 | 66°F | 42°F | 86°F 1955 | 26°F 2004 | 39% | 1% |
| May 5 | 67°F | 43°F | 91°F 1952 | 26°F 2005 | 39% | 1% |
| May 6 | 67°F | 43°F | 88°F 1959 | 27°F 1954 | 39% | 1% |
| May 7 | 68°F | 44°F | 84°F 1959 | 27°F 1989 | 39% | 1% |
| May 8 | 68°F | 44°F | 85°F 1964 | 29°F 1976 | 39% | 1% |
| May 9 | 68°F | 45°F | 87°F 1979 | 25°F 1966 | 39% | 1% |
| May 10 | 69°F | 45°F | 86°F 1979 | 22°F 1966 | 39% | 1% |
| May 11 | 69°F | 46°F | 86°F 1979 | 28°F 1966 | 39% | 0% |
| May 12 | 70°F | 46°F | 87°F 2022 | 26°F 1994 | 39% | 0% |
| May 13 | 70°F | 46°F | 89°F 2022 | 26°F 1997 | 39% | 0% |
| May 14 | 71°F | 47°F | 88°F 1991 | 30°F 2013 | 39% | 0% |
| May 15 | 71°F | 47°F | 88°F 1991 | 29°F 2016 | 39% | 0% |
| May 16 | 72°F | 48°F | 87°F 1962 | 24°F 1997 | 38% | 0% |
| May 17 | 72°F | 48°F | 89°F 1962 | 32°F 1993 | 38% | 0% |
| May 18 | 72°F | 49°F | 89°F 1962 | 28°F 1997 | 38% | 0% |
| May 19 | 73°F | 49°F | 91°F 1962 | 27°F 1993 | 38% | 0% |
| May 20 | 73°F | 50°F | 93°F 1975 | 34°F 1954 | 38% | 0% |
| May 21 | 74°F | 50°F | 89°F 1977 | 24°F 1997 | 38% | 0% |
| May 22 | 74°F | 51°F | 88°F 1970 | 27°F 2002 | 38% | 0% |
| May 23 | 74°F | 51°F | 89°F 1970 | 29°F 1963 | 38% | 0% |
| May 24 | 75°F | 52°F | 88°F 1977 | 31°F 1958 | 37% | 0% |
| May 25 | 75°F | 52°F | 90°F 2010 | 32°F 1988 | 37% | 0% |
| May 26 | 76°F | 53°F | 88°F 1977 | 31°F 1992 | 37% | 0% |
| May 27 | 76°F | 53°F | 93°F 1985 | 31°F 1961 | 37% | 0% |
| May 28 | 76°F | 54°F | 93°F 2012 | 35°F 1971 | 37% | 0% |
| May 29 | 77°F | 54°F | 94°F 1991 | 33°F 1964 | 37% | 0% |
| May 30 | 77°F | 54°F | 91°F 1991 | 33°F 1996 | 36% | 0% |
| May 31 | 77°F | 55°F | 91°F 1988 | 32°F 2021 | 36% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (CDT).
- May 1
- sunrise 5:49 AM, sunset 7:54 PM
- May 31
- sunrise 5:20 AM, sunset 8:23 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.