Ontario (CA)
December
Weather in Ontario, California for December 2026
Your guide to Ontario weather in December - trends and predictions
In general, the average temperature in Ontario at the beginning of December is 21 °C. As the month progressed, temperatures tended to significantly cool down, reaching an average of 16 °C by the end of December.
Ontario experiences moderate rainfall in December, with an average of 10 rainy days and a total precipitation of 188 mm.
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Temperatures
Rain 🌧️
More
21
Dry days
10
Rainy days
0
Snow days
19°/10°
Temperatures
9 km/h
Avg max wind
44 %
Avg humidity
Ontario Weather December
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Temperatures trend during December in Ontario
See the weather trend as well as the moving average line
December weather in Ontario day by day
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| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| Dec. 1 |  Sunny | 20° /10° | 0 mm | 5 | |
| Dec. 2 | Sunny | 19° /8° | 0 mm | 5 | |
| Dec. 3 | Sunny | 20° /8° | 0 mm | 5 | |
| Dec. 4 |  Overcast | 21° /9° | 0 mm | 5 | |
| Dec. 5 | Sunny | 23° /10° | 0 mm | 6 | |
| Dec. 6 | Sunny | 22° /11° | 0 mm | 6 | |
| Dec. 7 |  Partly cloudy | 22° /10° | 0 mm | 6 | |
| Dec. 8 | Sunny | 21° /10° | 0 mm | 6 | |
| Dec. 9 | Sunny | 21° /9° | 0 mm | 6 | |
| Dec. 10 | Sunny | 23° /9° | 0 mm | 6 | |
| Dec. 11 | Overcast | 23° /10° | 0 mm | 6 | |
| Dec. 12 | Sunny | 18° /9° | 0 mm | 5 | |
| Dec. 13 | Sunny | 18° /8° | 0 mm | 5 | |
| Dec. 14 | Overcast | 20° /11° | 0 mm | 5 | |
| Dec. 15 | Partly cloudy | 22° /8° | 0 mm | 6 | |
| Dec. 16 | Sunny | 23° /13° | 0 mm | 6 | |
| Dec. 17 | Partly cloudy | 23° /11° | 0 mm | 6 | |
| Dec. 18 | Sunny | 24° /14° | 0.2 mm | 6 | |
| Dec. 19 |  Light rain shower | 20° /11° | 2.9 mm | 5 | |
| Dec. 20 | Light rain shower | 19° /12° | 3.6 mm | 4 | |
| Dec. 21 |  Patchy light rain with thunder | 18° /10° | 2.2 mm | 3 | |
| Dec. 22 |  Cloudy | 18° /12° | 2.1 mm | 3 | |
| Dec. 23 | Sunny | 18° /9° | 1.1 mm | 4 | |
| Dec. 24 | Overcast | 15° /9° | 103.4 mm | 3 | |
| Dec. 25 | Partly cloudy | 16° /9° | 3.2 mm | 3 | |
| Dec. 26 | Partly cloudy | 15° /9° | 48.2 mm | 3 | |
| Dec. 27 | Overcast | 14° /8° | 0 mm | 3 | |
| Dec. 28 | Cloudy | 18° /8° | 0 mm | 4 | |
| Dec. 29 | Sunny | 18° /8° | 0 mm | 3 | |
| Dec. 30 | Light rain shower | 15° /7° | 3.2 mm | 3 | |
| Dec. 31 | Light rain shower | 16° /7° | 17.8 mm | 2 | |
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Important Notice
Our weather forecast for Ontario in December is based on the analysis of historical data rather than real-time forecast models. While this provides a general overview, weather conditions can change. We recommend that you check the Ontario forecast closer to your planned date for the most up-to-date weather information.
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Ontario in December - FAQ
What are the expected maximum and minimum temperatures in Ontario during December?
Enjoy moderate daytime temperatures of up to 19° and cooler nights around 10°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Ontario during December?
Significant rainfall exceeding 188 mm is expected in Ontario during December, occurring over more than 10 days. Preparing for wet conditions is recommended in your planning.
What are the typical wind conditions in Ontario during December?
The average wind speed in Ontario during December is 9 km/h, suggesting breezy to windy conditions, depending on your activities.
December rainfall patterns in Ontario
Explore the daily rainfall trends and prepare for Ontarios December weather 💧
Typically, Ontario has 10 rainy days in December with a total of 188 mm of rainfall.
UV exposure in Ontario during December
Stay informed about UV levels for safe outdoor activities throughout the month of December ☀️
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