Monticello, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Monticello, a city in Piatt County, Illinois.
Overnight
61°F
Patchy Fog
Patchy fog. Clear, with a low around 61. Southeast wind around 3 mph.
7-day forecast for Monticello
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 61°F | Patchy Fog | 3 mph SE | 0% |
| Tuesday | 85°F | Patchy Fog then Sunny | 6 mph S | 0% |
| Tuesday Night | 65°F | Mostly Clear | 6 mph SSE | 0% |
| Wednesday | 85°F | Mostly Sunny | 5 to 8 mph S | 8% |
| Wednesday Night | 67°F | Chance Showers And Thunderstorms | 7 mph S | 81% |
| Thursday | 81°F | Showers And Thunderstorms | 7 mph SSW | 81% |
| Thursday Night | 65°F | Chance Showers And Thunderstorms | 6 mph S | 33% |
| Friday | 82°F | Mostly Sunny | 5 mph SSW | 13% |
| Friday Night | 66°F | Slight Chance Showers And Thunderstorms | 3 mph SSW | 24% |
| Saturday | 85°F | Slight Chance Rain Showers then Mostly Sunny | 7 mph SSW | 18% |
| Saturday Night | 69°F | Mostly Clear | 5 to 9 mph SSW | 14% |
| Sunday | 87°F | Sunny | 9 to 14 mph SSW | 8% |
| Sunday Night | 71°F | Mostly Clear | 13 mph SSW | 11% |
| Monday | 88°F | Slight Chance Showers And Thunderstorms | 13 mph SSW | 16% |
Forecast source: National Weather Service (api.weather.gov) for Monticello (40.034, -88.574). Updated through the day.
Growing snapshot for Monticello
Last spring frost
Apr 23
First fall frost
Oct 13
Growing season
170 days
Hardiness zone
6a
More local growing data for Monticello: nearby ZIP 61856 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Champaign 9 Sw, Il (11.3 mi from Monticello). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.