Harvard, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Harvard, a city in Mchenry County, Illinois.
Overnight
61°F
Showers And Thunderstorms Likely
Showers and thunderstorms likely before 5am, then showers and thunderstorms. Some of the storms could produce heavy rain. Cloudy, with a low around 61. East southeast wind around 10 mph, with gusts as high as 20 mph. Chance of precipitation is 80%. New rainfall amounts between three quarters and one inch possible.
7-day forecast for Harvard
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 61°F | Showers And Thunderstorms Likely | 10 mph ESE | 79% |
| Saturday | 74°F | Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 to 10 mph ESE | 95% |
| Saturday Night | 61°F | Showers And Thunderstorms Likely then Showers And Thunderstorms | 5 to 10 mph NE | 76% |
| Sunday | 66°F | Showers And Thunderstorms Likely | 10 to 15 mph NE | 65% |
| Sunday Night | 54°F | Chance Rain Showers | 10 to 15 mph NE | 41% |
| Monday | 62°F | Chance Rain Showers | 15 mph ENE | 36% |
| Monday Night | 50°F | Chance Rain Showers | 10 to 15 mph NE | 36% |
| Tuesday | 61°F | Slight Chance Rain Showers | 10 to 15 mph NE | 18% |
| Tuesday Night | 49°F | Mostly Cloudy | 5 to 10 mph NE | 12% |
| Wednesday | 64°F | Partly Sunny | 5 to 10 mph NE | 6% |
| Wednesday Night | 50°F | Mostly Cloudy | 0 to 5 mph NNE | 5% |
| Thursday | 67°F | Partly Sunny | 0 to 5 mph NNE | 5% |
| Thursday Night | 51°F | Mostly Cloudy | 0 to 5 mph NE | 5% |
| Friday | 68°F | Mostly Sunny | 0 to 5 mph NNE | 5% |
Forecast source: National Weather Service (api.weather.gov) for Harvard (42.430, -88.621). Updated through the day.
Growing snapshot for Harvard
Last spring frost
Apr 28
First fall frost
Oct 12
Growing season
166 days
Hardiness zone
5b
More local growing data for Harvard: nearby ZIP 60033 weather · frost dates · planting calendar · Illinois frost dates
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Climate data from the nearest NOAA station, Marengo, Il (11 mi from Harvard). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.