Lacon, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Lacon, a city in Marshall County, Illinois.
Today
85°F
Mostly Sunny
Mostly sunny, with a high near 85. South southwest wind 2 to 7 mph.
7-day forecast for Lacon
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 85°F | Mostly Sunny | 2 to 7 mph SSW | 0% |
| Tonight | 66°F | Mostly Cloudy then Slight Chance Showers And Thunderstorms | 1 to 5 mph S | 20% |
| Wednesday | 81°F | Chance Showers And Thunderstorms | 1 to 7 mph SSW | 50% |
| Wednesday Night | 64°F | Showers And Thunderstorms | 0 to 5 mph SW | 87% |
| Thursday | 79°F | Showers And Thunderstorms Likely | 0 to 5 mph S | 72% |
| Thursday Night | 63°F | Slight Chance Showers And Thunderstorms then Partly Cloudy | 1 mph SSE | 15% |
| Friday | 82°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 0 mph | 19% |
| Friday Night | 65°F | Slight Chance Showers And Thunderstorms then Mostly Clear | 1 mph SSW | 19% |
| Saturday | 85°F | Mostly Sunny | 2 to 6 mph SSW | 9% |
| Saturday Night | 70°F | Mostly Clear | 3 to 8 mph SSW | 9% |
| Sunday | 87°F | Sunny | 8 to 12 mph SSW | 8% |
| Sunday Night | 71°F | Slight Chance Showers And Thunderstorms | 7 to 10 mph SSW | 24% |
| Monday | 87°F | Slight Chance Showers And Thunderstorms | 7 to 10 mph SSW | 24% |
| Monday Night | 71°F | Chance Showers And Thunderstorms | 9 mph SW | 34% |
Forecast source: National Weather Service (api.weather.gov) for Lacon (41.023, -89.406). Updated through the day.
Growing snapshot for Lacon
Last spring frost
Apr 20
First fall frost
Oct 17
Growing season
178 days
Hardiness zone
5b
More local growing data for Lacon: nearby ZIP 61540 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Lacon, Il (2.6 mi from Lacon). Frost dates are 1991–2020 averages, not a forecast. Page updated Aug 4, 2026.