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
| 15 May 2026 Friday 14.7 ° C / 58.5°F  Partly cloudy |
Feels Like : 13.4 ° C / 56°F Humidity : % 65 Pressure : 1014 mb Wind Speed : 19.4 kmph / 12.1 miles from SSE  Visibility : 16 km Precipitation (rainfall) : 0 mm Cloud (%) : 75 |
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 | |
|---|---|---|---|---|---|---|---|---|---|---|
| 15 May 2026 Friday |  Sunny |
13.3 ° C (55.9°F) |
30 ° C (86°F) |
20.3 ° C (68.5°F) |
% 62 | 0% | 8.4 | Sunrise:05:48 AM Sunset: 08:05 PM |
Moonrise:04:34 AM Moonset: 07:11 PM Moon Phase ( Waning Crescent ) |
|
| 16 May 2026 Saturday |  Patchy rain nearby |
18.6 ° C (65.5°F) |
27.6 ° C (81.7°F) |
22.1 ° C (71.7°F) |
% 82 | 65% | 2.7 | Sunrise:05:48 AM Sunset: 08:06 PM |
Moonrise:05:12 AM Moonset: 08:31 PM Moon Phase ( New Moon ) |
|
| 17 May 2026 Sunday | Sunny |
17.9 ° C (64.3°F) |
29 ° C (84.2°F) |
23.1 ° C (73.6°F) |
% 73 | 0% | 8.8 | Sunrise:05:47 AM Sunset: 08:07 PM |
Moonrise:05:58 AM Moonset: 09:49 PM Moon Phase ( Waxing Crescent ) |
|
| 18 May 2026 Monday | Patchy rain nearby |
20.5 ° C (68.9°F) |
30 ° C (86°F) |
24.9 ° C (76.7°F) |
% 70 | 81% | 8.9 | Sunrise:05:46 AM Sunset: 08:07 PM |
Moonrise:06:56 AM Moonset: 10:57 PM Moon Phase ( Waxing Crescent ) |
|
| 19 May 2026 Tuesday |  Moderate rain |
15.8 ° C (60.4°F) |
25.7 ° C (78.3°F) |
21.2 ° C (70.2°F) |
% 81 | 83% | 0.1 | Sunrise:05:45 AM Sunset: 08:08 PM |
Moonrise:08:05 AM Moonset: 11:54 PM Moon Phase ( Waxing Crescent ) |
|
| 20 May 2026 Wednesday | Patchy rain nearby |
14.6 ° C (58.2°F) |
19.7 ° C (67.5°F) |
17.1 ° C (62.8°F) |
% 80 | 84% | 4 | Sunrise:05:44 AM Sunset: 08:09 PM |
Moonrise:09:21 AM Moonset: No moonset Moon Phase ( Waxing Crescent ) |
|
| 21 May 2026 Thursday | Patchy rain nearby |
17.5 ° C (63.5°F) |
23.2 ° C (73.7°F) |
19.9 ° C (67.8°F) |
% 88 | 88% | 4 | Sunrise:05:44 AM Sunset: 08:10 PM |
Moonrise:10:36 AM Moonset: 12:39 AM Moon Phase ( Waxing Crescent ) |
|
| 22 May 2026 Friday | Partly Cloudy |
12.8 ° C (55.1°F) |
19.3 ° C (66.7°F) |
15.7 ° C (60.3°F) |
% 74 | 0% | 5 | Sunrise:05:43 AM Sunset: 08:11 PM |
Moonrise:11:49 AM Moonset: 01:14 AM Moon Phase ( Waxing Crescent ) |
|
| 23 May 2026 Saturday | Sunny |
10.5 ° C (51°F) |
22.4 ° C (72.3°F) |
16.1 ° C (61°F) |
% 69 | 0% | 5 | Sunrise:05:42 AM Sunset: 08:12 PM |
Moonrise:12:57 PM Moonset: 01:43 AM Moon Phase ( First Quarter ) |
|
| 24 May 2026 Sunday | Sunny |
9.4 ° C (49°F) |
20.9 ° C (69.7°F) |
15.2 ° C (59.3°F) |
% 69 | 0% | 5 | Sunrise:05:42 AM Sunset: 08:12 PM |
Moonrise:02:02 PM Moonset: 02:07 AM Moon Phase ( Waxing Gibbous ) |
|
| 25 May 2026 Monday | Moderate rain |
13.9 ° C (57°F) |
26.2 ° C (79.2°F) |
20.3 ° C (68.5°F) |
% 78 | 88% | 5 | Sunrise:05:41 AM Sunset: 08:13 PM |
Moonrise:03:04 PM Moonset: 02:30 AM Moon Phase ( Waxing Gibbous ) |
|
| 26 May 2026 Tuesday |  Heavy rain |
19.5 ° C (67.1°F) |
29 ° C (84.3°F) |
23.5 ° C (74.3°F) |
% 86 | 89% | 5 | Sunrise:05:41 AM Sunset: 08:14 PM |
Moonrise:04:06 PM Moonset: 02:52 AM Moon Phase ( Waxing Gibbous ) |
|
| 27 May 2026 Wednesday | Sunny |
22.6 ° C (72.8°F) |
33.3 ° C (92°F) |
27 ° C (80.6°F) |
% 72 | 0% | 7 | Sunrise:05:40 AM Sunset: 08:15 PM |
Moonrise:05:08 PM Moonset: 03:15 AM Moon Phase ( Waxing Gibbous ) |
|
| 28 May 2026 Thursday | Patchy rain nearby |
23 ° C (73.4°F) |
32.2 ° C (90°F) |
27.1 ° C (80.8°F) |
% 71 | 82% | 6 | Sunrise:05:40 AM Sunset: 08:15 PM |
Moonrise:06:09 PM Moonset: 03:40 AM Moon Phase ( Waxing Gibbous ) |
|
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