Lanark, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Lanark, a city in Carroll County, Illinois.
Today
84°F
Mostly Sunny then Slight Chance Showers And Thunderstorms
A slight chance of showers and thunderstorms after 5pm. Mostly sunny, with a high near 84. Southwest wind 5 to 10 mph. Chance of precipitation is 20%.
7-day forecast for Lanark
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 84°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 5 to 10 mph SW | 17% |
| Tonight | 65°F | Showers And Thunderstorms Likely | 0 to 5 mph NW | 90% |
| Wednesday | 75°F | Showers And Thunderstorms then Showers And Thunderstorms Likely | 5 mph NW | 77% |
| Wednesday Night | 59°F | Showers And Thunderstorms Likely | 0 to 5 mph N | 68% |
| Thursday | 78°F | Chance Rain Showers then Mostly Sunny | 0 to 5 mph NE | 32% |
| Thursday Night | 59°F | Mostly Clear | 0 mph | 7% |
| Friday | 80°F | Mostly Sunny | 0 to 5 mph SE | 4% |
| Friday Night | 63°F | Mostly Clear | 0 to 5 mph S | 8% |
| Saturday | 83°F | Mostly Sunny | 5 to 10 mph S | 11% |
| Saturday Night | 68°F | Mostly Clear then Slight Chance Showers And Thunderstorms | 5 to 10 mph S | 21% |
| Sunday | 85°F | Slight Chance Showers And Thunderstorms | 10 to 15 mph SW | 21% |
| Sunday Night | 68°F | Chance Showers And Thunderstorms | 5 to 10 mph S | 40% |
| Monday | 84°F | Chance Showers And Thunderstorms | 5 to 10 mph S | 38% |
| Monday Night | 68°F | Slight Chance Showers And Thunderstorms then Chance Showers And Thunderstorms | 5 to 10 mph NW | 42% |
Forecast source: National Weather Service (api.weather.gov) for Lanark (42.102, -89.833). Updated through the day.
Growing snapshot for Lanark
Last spring frost
May 2
First fall frost
Oct 7
Growing season
154 days
Hardiness zone
5a
More local growing data for Lanark: nearby ZIP 61046 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Mt Carroll, Il (8.8 mi from Lanark). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.