Quincy, IL Weather Forecast
Adams County, Illinois
Seven-day outlook
41–74°F across the weekThe week runs between 54° and 74°, with today the warmest day of it. There is no real trend across it: one day looks much like the next. Monday is the wettest day, peaking near 61%. 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 Quincy forecast
Quincy sits at 39.9337°N, 91.3793°W in Adams County, Illinois. 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
- Adams County
- Coordinates
- 39.9337°N, 91.3793°W
- Population
- 38,803 · 2023 estimate
- Land area
- 15.767 sq mi
Place data from the US Census Bureau. Coordinates are the Census internal point for Quincy, 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 Quincy?
The nearest Doppler radar is KLSX (St. Louis, MO), 93 miles to the SSE. 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 Quincy its center is about 8,600 ft above ground. At that range the beam overshoots the layer where severe weather organizes. The radar is describing the middle of the storm, not its base , which is why a warning for Quincy can look unsupported on the mosaic and still be right. Trust the warning over the picture.
The closest instrument actually measuring the air is KUIN · Quincy/Baldwin Fld on the ASOS/AWOS network, 9.7 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 Illinois observing network as of this build.
Forecasts near Quincy
- Palmyra, MO12 mi
- Hannibal, MO15 mi
- Canton, MO16 mi
- Monroe City, MO27 mi
- Hamilton, IL32 mi
- Keokuk, IA33 mi
- Louisiana, MO38 mi
- Pittsfield, IL38 mi
Elsewhere in Illinois
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