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Ontario, CA Weather Tomorrow

Tomorrow's forecast for Ontario includes an extended 5 day weather outlook with precipitation probability, daily and nightly weather conditions, high and low temperature trends, sunrise and sunset information, sky cover, wind speed, wind direction, and wind chill for the Ontario area and around San Bernardino county, California.
Updated: Sun Oct 18th 2026 1:15 PM PDT
Ontario, CA Weather – 10-18 – Sunny
85° / 72°
Sunny
Ontario may see a sunny day, with daytime highs of 85°F and overnight lows near 72°F. Wind will be moderate, blowing around 11mph on average and gusts of 21.5mph at 5 PM. The air will be relatively dry with average humidity levels below 30%, the maximum being 37% at 11 PM and 15% being its lowest at 2 PM. Barometric pressure is its highest of 29.94inHg at 10 PM, a lowest point of 29.89inHg at 3 PM with an avg 29.91inHg.
Ontario, CA Weather – 10-19 – Sunny
84° / 71°

Weather Tomorrow

Sunny
Ontario may see sunshine, with daytime highs of 84°F and overnight lows near 71°F. There's a very small chance of rainfall, only about 1%. Winds will be light at 10mph and gusts of 17.2mph at 6 PM. Humidity levels should be comfortable, sitting around 36% on average, the maximum being 50% at 11 PM and 26% being its lowest at 2 PM. Barometric pressure is its highest of 29.93inHg at 12 AM, a lowest point of 29.82inHg at 4 PM with an avg 29.88inHg.
Ontario, CA Weather – 10-20 – Sunny
81° / 68°
Sunny
Ontario could see sunshine with daytime highs of 81°F and nighttime lows near 68°F. There's a very small chance of rainfall, only about 2%. Wind will be moderate, blowing around 12mph on average and gusts of 22.4mph at 5 PM. Humidity levels should be comfortable, sitting around 51% on average, the maximum being 66% at 7 AM and 31% being its lowest at 2 PM. Barometric pressure is its highest of 29.89inHg at 11 PM, a lowest point of 29.8inHg at 4 PM with an avg 29.85inHg.
Ontario, CA Weather – 10-21 – Sunny
79° / 62°
Sunny
Highs will reach 79°F with lows near 62°F in Ontario, where a sunny day is. Rainfall predicted to have a 65% chance with an estimated 0.56in. Wind will be moderate, blowing around 17mph on average and gusts of 28.2mph at 4 PM. The humidity will be on the higher side, averaging about 61%, the maximum being 86% at 10 PM and 28% being its lowest at 2 PM. Barometric pressure is its highest of 29.92inHg at 9 AM, a lowest point of 29.8inHg at 3 PM with an avg 29.88inHg.
Ontario, CA Weather – 10-22 – Scattered Showers
70° / 63°
Scattered Showers
Highs will reach 70°F with lows near 63°F in Ontario, where passing showers are. Rainfall predicted to have a 74% chance with an estimated 0.39in. Wind will be moderate, blowing around 12mph on average and gusts of 21.3mph at 2 PM. The humidity will be on the higher side, averaging about 62%, the maximum being 74% at 7 AM and 44% being its lowest at 3 PM. Barometric pressure is its highest of 29.96inHg at 11 PM, a lowest point of 29.86inHg at 4 AM with an avg 29.9inHg.
Ontario, CA Weather – 10-23 – Scattered Showers
72° / 61°
Scattered Showers
In Ontario, on and off showers are set to occur with highs near 72°F and lows around 61°F. There's a moderate 36% chance of rainfall with an estimated 0.03in. Winds will be light at 8mph and gusts of 13.6mph at 11 AM. Humidity levels should be comfortable, sitting around 59% on average, the maximum being 75% at 5 AM and 40% being its lowest at 5 PM. Barometric pressure is its highest of 30inHg at 8 AM, a lowest point of 29.91inHg at 5 PM with an avg 29.96inHg.

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