Monticello, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Monticello, a city in Piatt County, Illinois.
This Afternoon
84°F
Mostly Sunny
Mostly sunny. High near 84, with temperatures falling to around 76 in the afternoon. East northeast wind around 10 mph. New rainfall amounts less than a tenth of an inch possible.
7-day forecast for Monticello
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 84°F | Mostly Sunny | 10 mph ENE | 11% |
| Tonight | 69°F | Partly Cloudy | 10 mph ESE | 6% |
| Saturday | 89°F | Slight Chance Showers And Thunderstorms | 9 mph S | 24% |
| Saturday Night | 69°F | Slight Chance Showers And Thunderstorms | 8 mph S | 24% |
| Sunday | 84°F | Chance Showers And Thunderstorms | 6 to 13 mph NNE | 49% |
| Sunday Night | 60°F | Chance Showers And Thunderstorms | 12 to 15 mph NE | 64% |
| Monday | 70°F | Showers And Thunderstorms Likely | 14 to 17 mph NE | 70% |
| Monday Night | 54°F | Showers And Thunderstorms Likely | 13 to 17 mph NE | 57% |
| Tuesday | 67°F | Chance Rain Showers | 16 mph NE | 34% |
| Tuesday Night | 52°F | Mostly Cloudy | 8 to 16 mph NNE | 9% |
| Wednesday | 69°F | Partly Sunny | 13 mph NNE | 3% |
| Wednesday Night | 53°F | Partly Cloudy | 6 to 13 mph NNE | 3% |
| Thursday | 71°F | Mostly Sunny | 7 to 10 mph NNE | 3% |
| Thursday Night | 54°F | Partly Cloudy | 6 to 9 mph NNE | 4% |
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 Sep 19, 2026.