Today | Weather | Monday, January 19, 2026

Weather in Ontario, California

06:07 PM
Now
Cloudy Night
68° F
Feels Like 64°
Precipitation 0 %
Wind 7 mph
Humidity 32 %
Today
Sunny Weather
Day 77°
Night 50°
Precipitation 0 %
Wind 4 mph
UV Index (0 - 11+) 3

Ontario Weather Forecast Updated

1 minute ago
Last updated on
Weather Forecast History
Last Year's Weather on This Day (January 19, 2025)
Partly Sunny with Showers

Day

57°

Night

43°

Wind

4 mph

UV Index

3

Precipitation

55 %

Air Quality in Ontario

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

Pollutant Concentrations:

PM2.5 41.07 µg/m³
PM10 48.86 µg/m³
O3 0.059 ppm
NO2 2.6 ppb
SO2 0.8 ppb
CO 0.26 ppm
NH3 0.24 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)
PM2.541.07 µg/m³
PM1048.86 µg/m³
O3115.38 µg/m³
NO24.84 µg/m³
SO22.2 µg/m³
CO295.22 µg/m³
NH30.24 µg/m³
NO0 µg/m³