St. Clair Weather Forecast 15 Days, Weather in St. Clair Today
Current weather conditions and 15 day weather forecast for St. Clair, 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 St. Clair
| 09 August 2026 Sunday 26.8 ° C / 80.2°F  Clear |
Feels Like : 29 ° C / 84.2°F Humidity : % 76 Pressure : 1016 mb Wind Speed : 12.6 kmph / 7.8 miles from SSE  Visibility : 10 km Precipitation (rainfall) : 0 mm Cloud (%) : 0 |
15 day weather forecast for St. Clair, IL, USA
Weather Forecast for next 15 Days for St. Clair 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 St. Clair, 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 | |
|---|---|---|---|---|---|---|---|---|---|---|
| 08 August 2026 Saturday | Sunny |
22.4 ° C (72.3°F) |
34.5 ° C (94.1°F) |
28.1 ° C (82.7°F) |
% 69 | 5% | 8.2 | Sunrise:06:08 AM Sunset: 08:03 PM |
Moonrise:12:48 AM Moonset: 04:42 PM Moon Phase ( Waning Crescent ) |
|
| 09 August 2026 Sunday | Sunny |
22.4 ° C (72.3°F) |
35 ° C (94.9°F) |
28.5 ° C (83.2°F) |
% 72 | 6% | 7.9 | Sunrise:06:08 AM Sunset: 08:01 PM |
Moonrise:01:46 AM Moonset: 05:45 PM Moon Phase ( Waning Crescent ) |
|
| 10 August 2026 Monday | Sunny |
23.9 ° C (74.9°F) |
37.2 ° C (99°F) |
30.1 ° C (86.3°F) |
% 58 | 3% | 8.2 | Sunrise:06:09 AM Sunset: 08:00 PM |
Moonrise:02:56 AM Moonset: 06:39 PM Moon Phase ( New Moon ) |
|
| 11 August 2026 Tuesday | Sunny |
23.2 ° C (73.8°F) |
38.5 ° C (101.3°F) |
30.5 ° C (87°F) |
% 55 | 57% | 8.6 | Sunrise:06:10 AM Sunset: 07:59 PM |
Moonrise:04:14 AM Moonset: 07:23 PM Moon Phase ( New Moon ) |
|
| 12 August 2026 Wednesday | Sunny |
22.5 ° C (72.4°F) |
32.7 ° C (90.9°F) |
26.9 ° C (80.4°F) |
% 73 | 59% | 7.4 | Sunrise:06:11 AM Sunset: 07:58 PM |
Moonrise:05:35 AM Moonset: 07:58 PM Moon Phase ( New Moon ) |
|
| 13 August 2026 Thursday |  Patchy rain nearby |
21.3 ° C (70.3°F) |
26.3 ° C (79.3°F) |
23.1 ° C (73.5°F) |
% 94 | 90% | 6 | Sunrise:06:12 AM Sunset: 07:57 PM |
Moonrise:06:54 AM Moonset: 08:29 PM Moon Phase ( New Moon ) |
|
| 14 August 2026 Friday | Patchy rain nearby |
20.7 ° C (69.2°F) |
24.2 ° C (75.6°F) |
22.3 ° C (72.2°F) |
% 93 | 76% | 5 | Sunrise:06:13 AM Sunset: 07:55 PM |
Moonrise:08:11 AM Moonset: 08:56 PM Moon Phase ( Waxing Crescent ) |
|
| 15 August 2026 Saturday | Patchy rain nearby |
19.5 ° C (67.1°F) |
26.1 ° C (79°F) |
22.3 ° C (72.1°F) |
% 87 | 77% | 7 | Sunrise:06:14 AM Sunset: 07:54 PM |
Moonrise:09:25 AM Moonset: 09:22 PM Moon Phase ( Waxing Crescent ) |
|
| 16 August 2026 Sunday |  Fog |
19 ° C (66.1°F) |
28.4 ° C (83.1°F) |
23.1 ° C (73.6°F) |
% 88 | 55% | 7 | Sunrise:06:15 AM Sunset: 07:53 PM |
Moonrise:10:36 AM Moonset: 09:49 PM Moon Phase ( Waxing Crescent ) |
|
| 17 August 2026 Monday | Fog |
20.5 ° C (68.9°F) |
28.4 ° C (83.1°F) |
23.8 ° C (74.9°F) |
% 88 | 46% | 7 | Sunrise:06:16 AM Sunset: 07:51 PM |
Moonrise:11:47 AM Moonset: 10:17 PM Moon Phase ( Waxing Crescent ) |
|
| 18 August 2026 Tuesday | Fog |
20.8 ° C (69.4°F) |
27.5 ° C (81.4°F) |
23.8 ° C (74.8°F) |
% 88 | 81% | 7 | Sunrise:06:17 AM Sunset: 07:50 PM |
Moonrise:12:56 PM Moonset: 10:49 PM Moon Phase ( First Quarter ) |
|
| 19 August 2026 Wednesday | Sunny |
20.2 ° C (68.4°F) |
30.3 ° C (86.5°F) |
24.7 ° C (76.5°F) |
% 78 | 9% | 8 | Sunrise:06:17 AM Sunset: 07:49 PM |
Moonrise:02:03 PM Moonset: 11:27 PM Moon Phase ( First Quarter ) |
|
| 20 August 2026 Thursday | Sunny |
15 ° C (59°F) |
24.5 ° C (76.1°F) |
19.9 ° C (67.9°F) |
% 74 | 7% | 6 | Sunrise:06:18 AM Sunset: 07:47 PM |
Moonrise:03:07 PM Moonset: Does not set today Moon Phase ( First Quarter ) |
|
| 21 August 2026 Friday | Patchy rain nearby |
14.6 ° C (58.4°F) |
24.3 ° C (75.8°F) |
19 ° C (66.3°F) |
% 75 | 63% | 6 | Sunrise:06:19 AM Sunset: 07:46 PM |
Moonrise:04:05 PM Moonset: 12:10 AM Moon Phase ( First Quarter ) |
|
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