Swansea, IL Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Swansea, a village in St. Clair County, Illinois.
This Afternoon
98°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms. Sunny, with a high near 98. Heat index values as high as 107. Southwest wind around 3 mph. Chance of precipitation is 30%.
7-day forecast for Swansea
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 98°F | Chance Showers And Thunderstorms | 3 mph SW | 26% |
| Tonight | 73°F | Slight Chance Showers And Thunderstorms then Mostly Clear | 5 mph SE | 24% |
| Saturday | 98°F | Mostly Sunny | 3 to 8 mph SW | 6% |
| Saturday Night | 74°F | Partly Cloudy | 5 mph S | 1% |
| Sunday | 94°F | Mostly Sunny then Slight Chance Showers And Thunderstorms | 3 to 7 mph W | 17% |
| Sunday Night | 68°F | Slight Chance Showers And Thunderstorms then Chance Showers And Thunderstorms | 8 mph N | 54% |
| Monday | 82°F | Showers And Thunderstorms Likely | 6 to 10 mph N | 67% |
| Monday Night | 62°F | Showers And Thunderstorms Likely | 7 to 12 mph N | 67% |
| Tuesday | 72°F | Chance Rain Showers then Mostly Cloudy | 12 mph N | 27% |
| Tuesday Night | 55°F | Mostly Cloudy | 6 to 12 mph N | 6% |
| Wednesday | 75°F | Mostly Sunny | 9 mph N | 3% |
| Wednesday Night | 56°F | Partly Cloudy | 3 to 8 mph N | 2% |
| Thursday | 77°F | Mostly Sunny | 3 to 8 mph N | 2% |
| Thursday Night | 58°F | Partly Cloudy | 3 to 7 mph N | 2% |
Forecast source: National Weather Service (api.weather.gov) for Swansea (38.552, -89.988). Updated through the day.
Growing snapshot for Swansea
Last spring frost
Apr 12
First fall frost
Oct 20
Growing season
189 days
Hardiness zone
7a
More local growing data for Swansea: nearby ZIP 62226 weather · frost dates · planting calendar · Illinois frost dates
Nearby towns & communities
Belleville
Brooklyn
Cahokia Heights
Caseyville
Darmstadt
Dupo
East St. Louis
Fairmont City
Fairview Heights
Fayetteville
Floraville
Freeburg
Lebanon
Lenzburg
Marissa
Mascoutah
Millstadt
New Athens
O'Fallon
Paderborn
Rentchler
Sauget
Scott AFB
Shiloh
Smithton
St. Libory
Summerfield
Washington Park
Climate data from the nearest NOAA station, Belleville Siu Rsch, Il (8.4 mi from Swansea). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 18, 2026.