Today | Weather | Friday, September 11, 2026

Weather in St. Louis, Missouri

03:26 AM
Now
Foggy Weather
70° F
Feels Like 70°
Precipitation 2 %
Wind 5 mph
Humidity 97 %
Today
Cloudy Weather
Day 81°
Night 70°
Precipitation 25 %
Wind 6 mph
UV Index (0 - 11+) 3

St. Louis Weather Forecast Updated

Last updated on
Weather Forecast History
Last Year's Weather on This Day (September 11, 2025)
Cloudy Night

Day

90°

Night

63°

Wind

5 mph

Precipitation

1 %

Air Quality in St. Louis

NOW
45 AQI
Good air quality Dominant pollutant: PM2.5

Pollutant Concentrations:

PM2.5 10.79 µg/m³
PM10 11.21 µg/m³
O3 0.010 ppm
NO2 3 ppb
SO2 0.6 ppb
CO 0.14 ppm
NH3 0.03 µg/m³
NO 0 µg/m³
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide
NH3 – Ammonia
NO – Nitric oxide

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)
PM2.510.79 µg/m³
PM1011.21 µg/m³
O319.84 µg/m³
NO25.7 µg/m³
SO21.58 µg/m³
CO163.43 µg/m³
NH30.03 µg/m³
NO0 µg/m³