Mason City, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Mason City, a city in Mason County, Illinois.
Tonight
71°F
Partly Cloudy
Partly cloudy, with a low around 71. East southeast wind around 8 mph, with gusts as high as 18 mph. New rainfall amounts less than a tenth of an inch possible.
7-day forecast for Mason City
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Tonight | 71°F | Partly Cloudy | 8 mph ESE | 5% |
| Saturday | 91°F | Slight Chance Rain Showers then Mostly Cloudy | 8 mph SSW | 15% |
| Saturday Night | 68°F | Slight Chance Showers And Thunderstorms | 7 mph S | 38% |
| Sunday | 82°F | Showers And Thunderstorms Likely | 2 to 12 mph N | 62% |
| Sunday Night | 60°F | Showers And Thunderstorms Likely | 8 to 13 mph NE | 65% |
| Monday | 69°F | Showers And Thunderstorms Likely | 9 to 13 mph ENE | 65% |
| Monday Night | 55°F | Chance Showers And Thunderstorms | 8 to 14 mph NE | 47% |
| Tuesday | 67°F | Slight Chance Rain Showers then Mostly Cloudy | 10 mph NE | 24% |
| Tuesday Night | 51°F | Mostly Cloudy | 5 to 10 mph NNE | 5% |
| Wednesday | 70°F | Partly Sunny | 8 mph NNE | 3% |
| Wednesday Night | 53°F | Partly Cloudy | 2 to 7 mph NNE | 1% |
| Thursday | 71°F | Mostly Sunny | 3 to 7 mph NNE | 3% |
| Thursday Night | 55°F | Partly Cloudy | 2 to 6 mph NE | 3% |
| Friday | 73°F | Mostly Sunny | 3 to 7 mph NNE | 3% |
Forecast source: National Weather Service (api.weather.gov) for Mason City (40.202, -89.697). Updated through the day.
Growing snapshot for Mason City
Last spring frost
Apr 17
First fall frost
Oct 18
Growing season
182 days
Hardiness zone
6a
More local growing data for Mason City: nearby ZIP 62664 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Climate data from the nearest NOAA station, Mason City 4Se, Il (5.1 mi from Mason City). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.