5-day weather forecast St. Louis Sep 12, 2026
29°Weather forecast St. Louis Saturday Sep 12, 2026: overcast, temperature from 22 °C to 29 °C.
Precipitation probability 23%. Wind up to 3.61 m/s (gusts 7.42 m/s). Air humidity 48–80%, atmospheric pressure 758–761 mm Hg, UV index up to 7.3.
Weather Alerts
Air Quality Alert issued September 8 at 1:42AM CDT by NWS St Louis MO
Air Quality Alert
The St. Louis Clean Air Partnership has issued an air quality alert
for the St. Louis metropolitan area from 10 AM this morning to 8 PM
CDT this evening.
An Orange air quality forecast means that maximum ozone
concentrations are expected to reach levels that pose a health risk.
Adverse health effects increase as air quality deteriorates. Ground-
level ozone is an air contaminant which can cause breathing
difficulties for children, older adults, as well as persons with
respiratory problems.
Reducing outdoor physical activity is recommended. If it is a
regularly scheduled work day you are urged to consider
telecommuting, carpooling, or utilizing public transit. Avoid
excessive idling and do not top off when refueling motor vehicles.
The use of gasoline-powered lawn equipment should be reduced or
postponed until late in the day.
For more information visit the St. Louis Clean Air Partnership at
http://cleanair-stlouis.com/
For current Air Quality Index (AQI) values visit
https://www.airnow.gov/
5 days at a glance — tap a day to open it
Sunrise 06:39
Sunset 19:14
Sunset 19:14
New Moon3% illuminated
Moonrise 08:13 · Moonset 19:48
Moonrise 08:13 · Moonset 19:48
Chart
Table
| Time | Weather | Temperature | Rain chance | Cloud cover | Humidity | Pressure | Wind | UV Index |
|---|---|---|---|---|---|---|---|---|
| 00:00 |  Clear | 24 °C | 5% | 0% | 67% | 758 mm Hg | SE 128° 2.5 (5.42) m/s | 0 |
| 01:00 | Clear | 24 °C | 5% | 0% | 69% | 759 mm Hg | SE 133° 2.69 (5) m/s | 0 |
| 02:00 | Clear | 24 °C | 6% | 5% | 70% | 759 mm Hg | SSE 152° 3.11 (7.42) m/s | 0 |
| 03:00 | Clear | 23 °C | 7% | 5% | 73% | 759 mm Hg | S 189° 2.31 (6.19) m/s | 0 |
| 04:00 |  Overcast | 23 °C | 21% | 100% | 76% | 758 mm Hg | SSE 168° 2.39 (5.61) m/s | 0 |
| 05:00 | Overcast | 23 °C | 21% | 95% | 77% | 759 mm Hg | S 176° 2.19 (5.31) m/s | 0 |
| 06:00 | Clear | 22 °C | 9% | 6% | 79% | 759 mm Hg | S 183° 2.31 (5.42) m/s | 0 |
| 07:00 |  Sunny | 22 °C | 10% | 12% | 80% | 760 mm Hg | SW 218° 2.11 (5.19) m/s | 0 |
| 08:00 |  Cloudy | 23 °C | 15% | 72% | 74% | 761 mm Hg | SW 232° 2.61 (5.72) m/s | 0.4 |
| 09:00 | Sunny | 25 °C | 5% | 9% | 65% | 760 mm Hg | SSW 192° 3.11 (4.81) m/s | 1.5 |
| 10:00 | Overcast | 27 °C | 12% | 94% | 56% | 761 mm Hg | SSW 210° 3.11 (4.53) m/s | 3.2 |
| 11:00 | Overcast | 28 °C | 12% | 99% | 53% | 761 mm Hg | W 259° 3.61 (5.11) m/s | 5.2 |
| 12:00 | Overcast | 26 °C | 15% | 100% | 62% | 761 mm Hg | WSW 249° 2.81 (4.19) m/s | 6.7 |
| 13:00 |  Patchy rain possible | 26 °C | 23% (0.11 mm/hr) | 100% | 63% | 761 mm Hg | SW 223° 2.81 (4.42) m/s | 7.3 |
| 14:00 | Patchy rain possible | 28 °C | 23% (0.14 mm/hr) | 100% | 58% | 761 mm Hg | WSW 247° 3.19 (4.42) m/s | 6.8 |
| 15:00 | Overcast | 28 °C | 13% | 100% | 57% | 761 mm Hg | WSW 245° 3.39 (3.92) m/s | 5.4 |
| 16:00 | Patchy rain possible | 29 °C | 15% (0.03 mm/hr) | 100% | 55% | 761 mm Hg | WSW 253° 2.81 (3.39) m/s | 3.2 |
| 17:00 | Overcast | 28 °C | 12% | 95% | 56% | 761 mm Hg | W 274° 1.89 (2.83) m/s | 1.4 |
| 18:00 | Overcast | 27 °C | 14% | 100% | 60% | 761 mm Hg | W 270° 2.19 (4.11) m/s | 0.4 |
| 19:00 | Overcast | 26 °C | 15% | 100% | 63% | 761 mm Hg | WNW 285° 2.81 (5.61) m/s | 0 |
| 20:00 |  Cloudy | 29 °C | 9% | 86% | 48% | 760 mm Hg | E 85° 1.19 (3.03) m/s | 0 |
| 21:00 | Overcast | 28 °C | 12% | 97% | 54% | 761 mm Hg | ENE 65° 1.31 (1.44) m/s | 0 |
| 22:00 | Overcast | 26 °C | 16% | 100% | 65% | 761 mm Hg | NW 322° 1.69 (2.69) m/s | 0 |
| 23:00 | Overcast | 24 °C | 17% | 100% | 68% | 761 mm Hg | NW 324° 2.11 (2.72) m/s | 0 |
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Data Sources & Methodology
Our weather forecasts are powered by a professional weather data provider that aggregates data from national weather services, satellite observations, radar networks, and over 80,000 weather stations worldwide. Forecast data is updated multiple times daily. We convert raw data into clear summaries — wind speed in m/s, pressure in mmHg — so you can plan your day with confidence.