5-day weather forecast St. Louis Sep 12, 2026

26°22° · Overcast

Weather forecast St. Louis Saturday Sep 12, 2026: overcast, temperature from 22 °C to 26 °C.

Precipitation probability 36%. Wind up to 4.81 m/s (gusts 9.81 m/s). Air humidity 52–91%, atmospheric pressure 758–762 mm Hg, UV index up to 6.

Weather Alerts

WarningSep 7, 05:53 PM — Sep 9, 12:00 AMTranslate with Google

Air Quality Alert issued September 7 at 5:53PM 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 to 8 PM CDT Tuesday. 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/

WarningSep 7, 03:40 PM — Sep 8, 03:45 PMTranslate with Google

Air Quality Alert issued September 7 at 3:40PM CDT by NWS St Louis MO

Air Quality Alert

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Sunrise 06:39
Sunset 19:14

New Moon3% illuminated
Moonrise 08:13 · Moonset 19:48

Chart

Table

← Fri, Sep 11

Sat, Sep 12, 2026

Forecast from 22 °C to 26 °C and precipitation

Temperature & Precipitation
Time	00:00	01:00	02:00	03:00	04:00	05:00	06:00	07:00	08:00	09:00	10:00	11:00	12:00	13:00	14:00	15:00	16:00	17:00	18:00	19:00	20:00	21:00	22:00	23:00
Temperature (°C)	26	25	24	24	24	24	23	22	24	26	23	22	22	22	23	25	26	26	26	26	25	25	25	25
Precipitation (mm/hr)	0	0	0	0	0	0	0.08	0	0	0	0.17	0.1	0.1	0	0	0	0	0	0	0	0	0	0	0

Cloud cover and precipitation probability

Cloud cover & Rain chance
Time	00:00	01:00	02:00	03:00	04:00	05:00	06:00	07:00	08:00	09:00	10:00	11:00	12:00	13:00	14:00	15:00	16:00	17:00	18:00	19:00	20:00	21:00	22:00	23:00
Cloud cover (%)	100	7	9	100	100	0	73	100	100	69	100	100	100	100	100	100	100	100	100	100	68	36	4	15
Rain chance (%)	12	4	5	17	17	6	22	24	17	10	32	32	36	30	25	21	17	17	17	18	13	10	8	9

Wind speed and direction

Wind & Wind gust
Time	00:00	01:00	02:00	03:00	04:00	05:00	06:00	07:00	08:00	09:00	10:00	11:00	12:00	13:00	14:00	15:00	16:00	17:00	18:00	19:00	20:00	21:00	22:00	23:00
Wind (m/s)	2.69	2.39	2.39	2.39	2.19	2	2.69	2.39	2.5	3.81	4.81	4	3.19	2.39	1.89	1.31	0.81	0.89	1	1.11	1	1	0.89	1.11
Wind gust (m/s)	6	6.42	6.33	5.92	5.14	4.22	5.92	6.83	7.42	6.92	9.81	8.31	6.81	5.31	4	2.61	1.33	1.31	1.19	1.11	1.11	1	1.03	1.19
Wind direction (°)	SSE 156°	S 186°	S 188°	SSW 192°	S 189°	S 176°	W 264°	WSW 249°	SW 218°	W 264°	WNW 282°	WNW 283°	WNW 284°	WNW 285°	S 191°	E 96°	N 2°	ENE 64°	SE 125°	S 186°	S 169°	SSE 152°	SE 135°	ESE 117°

Air humidity

Humidity
Time	00:00	01:00	02:00	03:00	04:00	05:00	06:00	07:00	08:00	09:00	10:00	11:00	12:00	13:00	14:00	15:00	16:00	17:00	18:00	19:00	20:00	21:00	22:00	23:00
Humidity (%)	52	60	64	68	69	71	76	81	68	64	73	79	85	91	83	76	68	69	69	70	72	74	76	77

Atmospheric pressure

Pressure
Time	00:00	01:00	02:00	03:00	04:00	05:00	06:00	07:00	08:00	09:00	10:00	11:00	12:00	13:00	14:00	15:00	16:00	17:00	18:00	19:00	20:00	21:00	22:00	23:00
Pressure (mm Hg)	758	759	759	759	759	758	759	759	760	761	761	761	761	761	761	761	761	761	761	761	762	762	762	762

Ultraviolet index

UV Index
Time	00:00	01:00	02:00	03:00	04:00	05:00	06:00	07:00	08:00	09:00	10:00	11:00	12:00	13:00	14:00	15:00	16:00	17:00	18:00	19:00	20:00	21:00	22:00	23:00
UV Index	0	0	0	0	0	0	0	0	5	6	5	5	5	5	5	5	6	6	6	6	0	0	0	0

Air quality & pollen

Air quality is available for the first three days only.

← Fri, Sep 11

Sat, Sep 12, 2026

St. Louis on the map

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.

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