St. John, IN Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for St. John, a town in Lake County, Indiana.
Overnight
63°F
Chance Showers And Thunderstorms
A chance of showers and thunderstorms after 4am. Cloudy. Low around 63, with temperatures rising to around 65 overnight. Southeast wind around 10 mph. Chance of precipitation is 30%. New rainfall amounts between a tenth and quarter of an inch possible.
7-day forecast for St. John
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Overnight | 63°F | Chance Showers And Thunderstorms | 10 mph SE | 28% |
| Saturday | 78°F | Showers And Thunderstorms Likely | 5 to 10 mph SE | 95% |
| Saturday Night | 64°F | Showers And Thunderstorms Likely then Showers And Thunderstorms | 5 mph S | 89% |
| Sunday | 70°F | Showers And Thunderstorms Likely | 5 to 15 mph NNE | 62% |
| Sunday Night | 54°F | Chance Showers And Thunderstorms | 10 to 15 mph NE | 41% |
| Monday | 65°F | Chance Rain Showers | 10 to 15 mph NE | 43% |
| Monday Night | 50°F | Chance Rain Showers then Mostly Cloudy | 10 to 15 mph NE | 28% |
| Tuesday | 64°F | Slight Chance Rain Showers | 10 to 15 mph NE | 16% |
| Tuesday Night | 51°F | Mostly Cloudy | 5 to 10 mph NE | 14% |
| Wednesday | 65°F | Partly Sunny | 5 to 10 mph NNE | 10% |
| Wednesday Night | 52°F | Mostly Cloudy | 5 to 10 mph NNE | 6% |
| Thursday | 67°F | Partly Sunny | 5 to 10 mph NNE | 3% |
| Thursday Night | 52°F | Mostly Cloudy | 5 to 10 mph NNE | 3% |
| Friday | 70°F | Mostly Sunny | 5 to 10 mph NE | 3% |
Forecast source: National Weather Service (api.weather.gov) for St. John (41.442, -87.468). Updated through the day.
Growing snapshot for St. John
Last spring frost
Apr 23
First fall frost
Oct 20
Growing season
179 days
Hardiness zone
6a
More local growing data for St. John: nearby ZIP 46373 weather · frost dates · planting calendar · Indiana frost dates
Nearby towns & communities
Cedar Lake
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Lake Dalecarlia
Lake Station
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Lowell
Merrillville
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New Chicago
Ross
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Schneider
Shelby
Whiting
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Climate data from the nearest NOAA station, Park Forest, Il (11.6 mi from St. John). Frost dates are 1991–2020 averages, not a forecast. Page updated Sep 19, 2026.