Weather in O'Fallon, IL
O'Fallon, Wednesday, 14 October, 16:49
Overcast. Feels like 78°. High 77°, low 70°.
Monthly outlook for O'Fallon, IL: average high 69°, average low 51.9°. That is 2.7° above the climate normal for October. Precipitation is expected on 4 days (about 1.5 inches), against a normal of 5 days and 1.8 inches. The warmest day looks like 23 October (83.5°), the coolest 18 October (41.6°).
Ten-day blocks vs climate normal
| Period | Forecast high | Normal | Difference |
|---|---|---|---|
| 14 October – 23 October | 71.5° | 65.5° | +3.3° |
| 24 October – 2 November | 64.8° | 61.6° | +1.8° |
| 3 November – 12 November | at normal | 56.5° | — |
October records over 66 years
Climate normals and records are computed from the nearest reference point — Edwardsville (14 mi).
0.72
O'Fallon, Thursday, 15 October
Heavy rain. High 80°, low 69°.
0.26O'Fallon, Friday, 16 October
Heavy rain. High 66°, low 51°.
0
O'Fallon, Saturday, 17 October
Clear. High 58°, low 45°.
0O'Fallon, Sunday, 18 October
Clear. High 62°, low 42°.
0O'Fallon, Monday, 19 October
Overcast. High 65°, low 42°.
0
O'Fallon, Tuesday, 20 October
Partly cloudy. High 74°, low 46°.
0O'Fallon, Wednesday, 21 October
Clear. High 78°, low 57°.
0.02O'Fallon, Thursday, 22 October
Light rain. High 73°, low 63°.
0O'Fallon, Friday, 23 October
Partly cloudy. High 83°, low 65°.
0O'Fallon, Saturday, 24 October
Overcast. High 83°, low 58°.
0O'Fallon, Sunday, 25 October
Overcast. High 62°, low 49°.
0O'Fallon, Monday, 26 October
Overcast. High 61°, low 42°.
0O'Fallon, Tuesday, 27 October
Overcast. High 61°, low 42°.
0.23O'Fallon, Wednesday, 28 October
Rain. High 57°, low 47°.
0O'Fallon, Thursday, 29 October
Overcast. High 64°, low 46°.
0.12O'Fallon, Friday, 30 October
Climate normal for this date — 60-year average.
0.15
O'Fallon, Saturday, 31 October
Climate normal for this date — 60-year average.
0.18O'Fallon, Sunday, 1 November
Climate normal for this date — 60-year average.
0.08O'Fallon, Monday, 2 November
Climate normal for this date — 60-year average.
0.11O'Fallon, Tuesday, 3 November
Climate normal for this date — 60-year average.
0.16O'Fallon, Wednesday, 4 November
Climate normal for this date — 60-year average.
0.16O'Fallon, Thursday, 5 November
Climate normal for this date — 60-year average.
0.09O'Fallon, Friday, 6 November
Climate normal for this date — 60-year average.
0.08O'Fallon, Saturday, 7 November
Climate normal for this date — 60-year average.
0.04
O'Fallon, Sunday, 8 November
Climate normal for this date — 60-year average.
0.1O'Fallon, Monday, 9 November
Climate normal for this date — 60-year average.
0.13O'Fallon, Tuesday, 10 November
Climate normal for this date — 60-year average.
0.11O'Fallon, Wednesday, 11 November
Climate normal for this date — 60-year average.
0.09O'Fallon, Thursday, 12 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 O'Fallon, 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 O'Fallon, 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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