O'Fallon Weather Forecast 15 Days, Weather in O'Fallon Today
Current weather conditions and 15 day weather forecast for O'Fallon, Illinois, USA including weather daily high/low temperature, warnings, chance of precipitation, pressure, humidity/wind chill, rain risk, wind speed, cloud, pressure, and UV index.
Current weather conditions at O'Fallon
| 21 December 2025 Sunday 3.1 ° C / 37.6°F  Clear |
Feels Like : -0.4 ° C / 31.4°F Humidity : % 50 Pressure : 1025 mb Wind Speed : 13.7 kmph / 8.5 miles from N  Visibility : 16 km Precipitation (rainfall) : 0 mm Cloud (%) : 0 |
15 day weather forecast for O'Fallon, IL, USA
Weather Forecast for next 15 Days for O'Fallon including weather warnings, temperature, rain, wind speed, cloud, snow, wind speed and wind direction, pressure and UV index.Here is weather for the next 15 days in O'Fallon, Illinois state, US. To see the daily forecast, scroll to the table below.
| Date | Weather forecast | Low temperature | High temperature | Avg. temperature | Humidity | Chance of rain | UV Index | Sun Position | Moon Position | |
|---|---|---|---|---|---|---|---|---|---|---|
| 21 December 2025 Sunday | Sunny |
-4 ° C (24.8°F) |
4.6 ° C (40.3°F) |
0.3 ° C (32.5°F) |
% 67 | 0% | 0.4 | Sunrise:07:14 AM Sunset: 04:42 PM |
Moonrise:08:48 AM Moonset: 06:04 PM Moon Phase ( Waxing Crescent ) |
|
| 22 December 2025 Monday |  Partly Cloudy |
-2.5 ° C (27.5°F) |
6.1 ° C (43°F) |
1.7 ° C (35.1°F) |
% 77 | 0% | 0.3 | Sunrise:07:14 AM Sunset: 04:42 PM |
Moonrise:09:27 AM Moonset: 07:08 PM Moon Phase ( Waxing Crescent ) |
|
| 23 December 2025 Tuesday |  Fog |
4.7 ° C (40.5°F) |
10.9 ° C (51.6°F) |
8 ° C (46.3°F) |
% 94 | 0% | 0.4 | Sunrise:07:15 AM Sunset: 04:43 PM |
Moonrise:09:58 AM Moonset: 08:13 PM Moon Phase ( Waxing Crescent ) |
|
| 24 December 2025 Wednesday |  Cloudy |
6 ° C (42.7°F) |
17 ° C (62.6°F) |
11.5 ° C (52.8°F) |
% 81 | 0% | 0.2 | Sunrise:07:15 AM Sunset: 04:43 PM |
Moonrise:10:26 AM Moonset: 09:19 PM Moon Phase ( Waxing Crescent ) |
|
| 25 December 2025 Thursday | Partly Cloudy |
15.2 ° C (59.3°F) |
22.5 ° C (72.5°F) |
17.5 ° C (63.5°F) |
% 83 | 0% | 0 | Sunrise:07:15 AM Sunset: 04:44 PM |
Moonrise:10:51 AM Moonset: 10:23 PM Moon Phase ( Waxing Crescent ) |
|
| 26 December 2025 Friday | Sunny |
3.4 ° C (38.1°F) |
11.3 ° C (52.4°F) |
10.2 ° C (50.3°F) |
% 63 | 0% | 4 | Sunrise:07:16 AM Sunset: 04:45 PM |
Moonrise:11:14 AM Moonset: 11:30 PM Moon Phase ( Waxing Crescent ) |
|
| 27 December 2025 Saturday | Sunny |
0.4 ° C (32.8°F) |
8.4 ° C (47.1°F) |
3.8 ° C (38.8°F) |
% 66 | 0% | 2 | Sunrise:07:16 AM Sunset: 04:45 PM |
Moonrise:11:38 AM Moonset: No moonset Moon Phase ( First Quarter ) |
|
| 28 December 2025 Sunday | Sunny |
2 ° C (35.6°F) |
11.8 ° C (53.3°F) |
6.1 ° C (42.9°F) |
% 66 | 0% | 3 | Sunrise:07:16 AM Sunset: 04:46 PM |
Moonrise:12:03 PM Moonset: 12:38 AM Moon Phase ( Waxing Gibbous ) |
|
| 29 December 2025 Monday | Partly Cloudy |
8.5 ° C (47.2°F) |
19.3 ° C (66.8°F) |
13.9 ° C (57.1°F) |
% 78 | 0% | 4 | Sunrise:07:17 AM Sunset: 04:47 PM |
Moonrise:12:32 PM Moonset: 01:50 AM Moon Phase ( Waxing Gibbous ) |
|
| 30 December 2025 Tuesday |  Patchy rain nearby |
13.6 ° C (56.5°F) |
17.1 ° C (62.8°F) |
16.1 ° C (60.9°F) |
% 88 | 87% | 4 | Sunrise:07:17 AM Sunset: 04:48 PM |
Moonrise:01:08 PM Moonset: 03:05 AM Moon Phase ( Waxing Gibbous ) |
|
| 31 December 2025 Wednesday | Patchy rain nearby |
8.9 ° C (48°F) |
10.3 ° C (50.6°F) |
10.1 ° C (50.1°F) |
% 88 | 86% | 3 | Sunrise:07:17 AM Sunset: 04:48 PM |
Moonrise:01:52 PM Moonset: 04:23 AM Moon Phase ( Waxing Gibbous ) |
|
| 01 January 2026 Thursday | Patchy rain nearby |
8.1 ° C (46.6°F) |
9.6 ° C (49.2°F) |
8.8 ° C (47.8°F) |
% 90 | 84% | 2 | Sunrise:07:17 AM Sunset: 04:49 PM |
Moonrise:02:47 PM Moonset: 05:40 AM Moon Phase ( Waxing Gibbous ) |
|
| 02 January 2026 Friday | Partly Cloudy |
6 ° C (42.9°F) |
12.7 ° C (54.9°F) |
8.8 ° C (47.9°F) |
% 85 | 0% | 3 | Sunrise:07:17 AM Sunset: 04:50 PM |
Moonrise:03:55 PM Moonset: 06:50 AM Moon Phase ( Waxing Gibbous ) |
|
| 03 January 2026 Saturday | Sunny |
6.9 ° C (44.4°F) |
14.6 ° C (58.3°F) |
10 ° C (50°F) |
% 82 | 0% | 3 | Sunrise:07:17 AM Sunset: 04:51 PM |
Moonrise:05:10 PM Moonset: 07:49 AM Moon Phase ( Full Moon ) |
|
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