Today | Weather | Wednesday, May 20, 2026

Weather in Watertown, South Dakota

04:52 PM
Now
Cloudy Weather
61° F
Feels Like 63°
Precipitation 0 %
Wind 11 mph
UV Index (0 - 11+) 3
Humidity 35 %
Today
Cloudy Weather
Day 63°
Night 43°
Precipitation 1 %
Wind 9 mph
UV Index (0 - 11+) 9
Overnight Frost 5 AM – 5 AM

Warning: High UV Index Today: 9

High risk of harm from unprotected sun exposure. Take precautions: wear a hat, sunglasses, and apply sunscreen regularly if you’ll be outdoors for extended periods.

Watertown Weather Forecast Updated

Last updated on

Air Quality in Watertown

NOW
40 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 0.71 µg/m³
PM10 0.76 µg/m³
O3 0.044 ppm
NO2 0.3 ppb
SO2 0 ppb
CO 0.10 ppm
NH3 4.43 µg/m³
NO 0.08 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)
PM2.50.71 µg/m³
PM100.76 µg/m³
O385.77 µg/m³
NO20.54 µg/m³
SO20.03 µg/m³
CO119.12 µg/m³
NH34.43 µg/m³
NO0.08 µg/m³