Mason City, IL Weather & Growing Conditions
Overnight
70°F
Partly Cloudy
Partly cloudy, with a low around 70. Southeast wind around 8 mph, with gusts as high as 17 mph.
7-day forecast
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 70°F | Partly Cloudy | 8 mph SE | 11% |
| Saturday | 90°F | Slight Chance Rain Showers then Mostly Cloudy | 8 mph SSW | 15% |
| Saturday Night | 68°F | Slight Chance Showers And Thunderstorms | 7 mph S | 40% |
| Sunday | 82°F | Showers And Thunderstorms Likely | 3 to 12 mph N | 62% |
| Sunday Night | 60°F | Showers And Thunderstorms Likely | 9 to 14 mph NE | 65% |
| Monday | 69°F | Showers And Thunderstorms Likely | 13 mph ENE | 65% |
| Monday Night | 55°F | Chance Showers And Thunderstorms | 9 to 14 mph NE | 47% |
| Tuesday | 66°F | Chance Rain Showers then Mostly Cloudy | 10 mph NE | 25% |
| Tuesday Night | 51°F | Mostly Cloudy | 6 to 10 mph NNE | 5% |
| Wednesday | 70°F | Partly Sunny | 8 mph NNE | 3% |
| Wednesday Night | 53°F | Partly Cloudy | 3 to 7 mph NNE | 1% |
| Thursday | 72°F | Mostly Sunny | 3 to 7 mph NNE | 3% |
| Thursday Night | 55°F | Partly Cloudy | 2 to 6 mph NE | 3% |
| Friday | 74°F | Mostly Sunny | 3 to 7 mph NNE | 3% |
Forecast source: National Weather Service (api.weather.gov). Updated through the day.
Growing snapshot for Mason City, IL
Last spring frost
Apr 17
First fall frost
Oct 18
Growing season
182 days
Hardiness zone
6a
Explore more for Mason City, IL: full frost dates · planting calendar · Illinois frost dates
Climate data from the nearest NOAA station, Mason City 4Se, Il (5.1 mi). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.