St. John, IN Weather Forecast
Lake County, Indiana
Seven-day outlook
40–70°F across the weekThe week runs between 46° and 70°, with today the warmest day of it. There is no real trend across it: one day looks much like the next. Saturday is the wettest day, peaking near 64%. 3 of the 7 days stay dry.
Forecasts come from the National Weather Service's own computer models, and current conditions from the nearest reporting weather station. Both are served through the weather API. A forecast is guidance, not a warning, and anything the Weather Service has actually issued is on the live map.
The written summaries on this page are generated from the forecast data above, not by a meteorologist. Each sentence is a reading of the same numbers you can see, and no forecaster has reviewed them.
About the St. John forecast
St. John sits at 41.4418°N, 87.4678°W in Lake County, Indiana. The forecast above is drawn for that point from the National Weather Service's own computer models: a seven-day outlook, and a finer-grained one covering the next eighteen hours where it reaches, and the radar and alert panels show what the Weather Service has out over the area right now.
- County
- Lake County
- Coordinates
- 41.4418°N, 87.4678°W
- Population
- 23,644 · 2023 estimate
- Land area
- 12.739 sq mi
Place data from the US Census Bureau. Coordinates are the Census internal point for St. John, and the forecast is for that location, not for every address inside the city limits, and a large city can have real weather differences from one side to the other.
How well can the network see St. John?
The nearest Doppler radar is KLOT (Chicago, IL), 34 miles to the WNW. A WSR-88D's lowest routine scan sits half a degree above horizontal, and the earth curves away beneath it, so by the time that beam reaches St. John its center is about 2,100 ft above ground. That is comfortably inside the useful range. The lowest scan passes low enough over St. John to show rotation in the part of a storm where tornadoes actually form. St. John is closer to its radar than 65% of US cities.
The closest instrument actually measuring the air is KIGQ · Chicago/Lansing Muni on the ASOS/AWOS network, 7.5 miles away. Near enough to be representative on most days, though a summer thunderstorm can soak one and miss the other entirely.
Beam height is the standard 4/3-earth approximation for the 0.5° scan and assumes normal refraction; it is where the center of the beam is, not its edges, and unusual temperature profiles bend it. Radar siting from the NWS WSR-88D network, station positions from the Indiana observing network as of this build.
Forecasts near St. John
- Schererville, IN3 mi
- Dyer, IN4 mi
- Cedar Lake, IN5 mi
- Sauk Village, IL6 mi
- Griffith, IN6 mi
- Crown Point, IN7 mi
- Lynwood, IL7 mi
- Highland, IN7 mi
Elsewhere in Indiana
IndianapolisFort WayneEvansvilleFishersSouth BendCarmelAll Indiana forecasts →