Weather in Decatur, IL
Decatur, Saturday, 17 October, 09:31
Clear. Feels like 38°. High 54°, low 39°.
Monthly outlook for Decatur, IL: average high 69.6°, average low 50.6°. That is 4.7° above the climate normal for October. Precipitation is expected on 4 days (about 0.9 inches), against a normal of 5 days and 1.9 inches. The warmest day looks like 27 October (78.9°), the coolest 17 October (39.1°).
Ten-day blocks vs climate normal
| Period | Forecast high | Normal | Difference |
|---|---|---|---|
| 17 October – 26 October | 68.8° | 62.1° | +3.7° |
| 27 October – 5 November | 71° | 58.5° | +7° |
| 6 November – 15 November | at normal | 53.1° | — |
October records over 66 years
Climate normals and records are computed from the nearest reference point — Lake City (13 mi).
0Decatur, Sunday, 18 October
Clear. High 62°, low 40°.
0Decatur, Monday, 19 October
Clear. High 66°, low 42°.
0
Decatur, Tuesday, 20 October
Mostly clear. High 68°, low 43°.
0Decatur, Wednesday, 21 October
Clear. High 70°, low 47°.
0Decatur, Thursday, 22 October
Clear. High 71°, low 47°.
0Decatur, Friday, 23 October
Clear. High 76°, low 53°.
0
Decatur, Saturday, 24 October
Overcast. High 73°, low 56°.
0Decatur, Sunday, 25 October
Overcast. High 76°, low 58°.
0Decatur, Monday, 26 October
Clear. High 72°, low 50°.
0Decatur, Tuesday, 27 October
Overcast. High 79°, low 61°.
0.28
Decatur, Wednesday, 28 October
Rain. High 71°, low 61°.
0.06Decatur, Thursday, 29 October
Light rain. High 65°, low 53°.
0.44Decatur, Friday, 30 October
Rain. High 76°, low 61°.
0.14Decatur, Saturday, 31 October
Light rain. High 72°, low 52°.
0Decatur, Sunday, 1 November
Clear. High 63°, low 45°.
0.09
Decatur, Monday, 2 November
Climate normal for this date — 60-year average.
0.09Decatur, Tuesday, 3 November
Climate normal for this date — 60-year average.
0.1Decatur, Wednesday, 4 November
Climate normal for this date — 60-year average.
0.11Decatur, Thursday, 5 November
Climate normal for this date — 60-year average.
0.08Decatur, Friday, 6 November
Climate normal for this date — 60-year average.
0.09Decatur, Saturday, 7 November
Climate normal for this date — 60-year average.
0.04Decatur, Sunday, 8 November
Climate normal for this date — 60-year average.
0.11
Decatur, Monday, 9 November
Climate normal for this date — 60-year average.
0.14Decatur, Tuesday, 10 November
Climate normal for this date — 60-year average.
0.1Decatur, Wednesday, 11 November
Climate normal for this date — 60-year average.
0.07Decatur, Thursday, 12 November
Climate normal for this date — 60-year average.
0.07Decatur, Friday, 13 November
Climate normal for this date — 60-year average.
0.09Decatur, Saturday, 14 November
Climate normal for this date — 60-year average.
0.11Decatur, Sunday, 15 November
Climate normal for this date — 60-year average.
About the monthly outlook
How accurate is a 30-day forecast?
The first 16 days come from weather models — reliable for the first 3–5 days and progressively less so after that. Days 17 through 30 for Decatur, IL are built from the climate normal, the 60-year average, so they show typical weather for those dates rather than a specific forecast.
What does "above normal" mean?
We compare the forecast against the climate normal for those exact calendar days, computed from 60 years of observations. The deviation shows how much the coming month differs from a typical one.
Where do the 66-year records come from?
They are real temperature extremes recorded in Decatur, IL since 1960: the highest and lowest reading for each calendar date, with the year it happened.
How often is it updated?
The forecast portion refreshes every hour; the climate portion is based on long-term data and stays stable.
Sun and moon today
Weather history
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