Today | Weather | Tuesday, January 20, 2026

Weather in Ontario, California

12:35 AM
Now
Cloudy Night
55° F
Feels Like 55°
Precipitation 0 %
Wind 6 mph
Humidity 53 %
Today
Sunny Weather
Day 77°
Night 50°
Precipitation 0 %
Wind 6 mph
UV Index (0 - 11+) 3

Ontario Weather Forecast Updated

Last updated on
Weather Forecast History
Last Year's Weather on This Day (January 20, 2025)
Windy Weather

Day

66°

Night

45°

Wind

17 mph

UV Index

3

Precipitation

0 %

Air Quality in Ontario

NOW
128 AQI
Unhealthy air quality for sensitive groups Dominant pollutant: PM2.5

Pollutant Concentrations:

PM2.5 46.54 µg/m³
PM10 54.49 µg/m³
O3 0.051 ppm
NO2 1.4 ppb
SO2 0.8 ppb
CO 0.30 ppm
NH3 0.18 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:

Members of sensitive groups may experience health effects. The general public is not likely to be affected.

Show raw pollutant concentrations (µg/m³)
PM2.546.54 µg/m³
PM1054.49 µg/m³
O3100.04 µg/m³
NO22.6 µg/m³
SO22.18 µg/m³
CO341.69 µg/m³
NH30.18 µg/m³
NO0 µg/m³