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Weather in Ontario, California for December 2025

Your guide to Ontario weather in December - trends and predictions

    Temperatures

  • Until now, December 2025 in Ontario has been nearly identical to the historical average, with a temperature of 21.4 °F (showing only a slight deviation of 0.5 °F).

  • The forecast for the upcoming days in Ontario predicts a temperature of 22.9 °F, which is slightly above the historical average.

  • In general, the average temperature in Ontario at the beginning of December is 21 °F. As the month progressed, temperatures tended to moderately fall, reaching an average of 20.3 °F by the end of December.

    • Rain 🌧️

  • Ontario experiences moderate rainfall in December, with an average of 6 rainy days and a total precipitation of 23.4 mm.

    • More

  • New! Chat with our AI weatherman - it’s amazing and free.

Average dry days
25
Dry days
Average rainy days
6
Rainy days
Average snowy days
0
Snow days
Average temperatures
19°/9°
Temperatures
Average wind speed
9 km/h
Avg max wind
Average humidity
40 %
Avg humidity

Ontario Weather December

Move between months or click on a day
November
January
Sun.Mon.Tue.Wed.Thu.Fri.Sat.
1
Sunny
20°
2
Sunny
19°
3
Sunny
20°
4
Overcast
21°
5
Sunny
23°
6
Sunny
22°
7
Partly cloudy
22°
8
Sunny
21°
9
Sunny
21°
10
Sunny
23°
11
Overcast
23°
12
Sunny
18°
13
Sunny
18°
14
Overcast
20°
15
Sunny
27°
16
Partly cloudy
26°
17
Sunny
26°
18
Sunny
25°
19
Partly cloudy
23°
20
Sunny
21°
21
Sunny
21°
22
Sunny
20°
23
Sunny
21°
24
Sunny
20°
25
Sunny
21°
26
Sunny
23°
27
Sunny
23°
28
Sunny
24°
29
Overcast
19°
30
Light rain shower
17°
31
Light rain shower
15°

Temperatures trend during December in Ontario

See the weather trend as well as the moving average line

December weather in Ontario day by day

Click on a date for more information
November January
Date Weather Temperatures Rain UV More
Dec. 1 Sunny
Sunny
 20° /10° 0 mm 5
Dec. 2 Sunny
Sunny
 19° /8° 0 mm 5
Dec. 3 Sunny
Sunny
 20° /8° 0 mm 5
Dec. 4 Overcast
Overcast
 21° /9° 0 mm 5
Dec. 5 Sunny
Sunny
 23° /10° 0 mm 6
Dec. 6 Sunny
Sunny
 22° /11° 0 mm 6
Dec. 7 Partly cloudy
Partly cloudy
 22° /10° 0 mm 6
Dec. 8 Sunny
Sunny
 21° /10° 0 mm 6
Dec. 9 Sunny
Sunny
 21° /9° 0 mm 6
Dec. 10 Sunny
Sunny
 23° /9° 0 mm 6
Dec. 11 Overcast
Overcast
 23° /10° 0 mm 6
Dec. 12 Sunny
Sunny
 18° /9° 0 mm 5
Dec. 13 Sunny
Sunny
 18° /8° 0 mm 5
Dec. 14 Overcast
Overcast
 20° /11° 0 mm 5
Dec. 15 Sunny
Sunny
 27° /10° 0 mm 0.6
Dec. 16 Partly cloudy
Partly cloudy
 26° /15° 0 mm 0.6
Dec. 17 Sunny
Sunny
 26° /16° 0 mm 0.6
Dec. 18 Sunny
Sunny
 25° /14° 0 mm 0.6
Dec. 19 Partly cloudy
Partly cloudy
 23° /15° 0 mm 0
Dec. 20 Sunny
Sunny
 21° /13° 0 mm 5
Dec. 21 Sunny
Sunny
 21° /13° 0 mm 5
Dec. 22 Sunny
Sunny
 20° /13° 0 mm 5
Dec. 23 Sunny
Sunny
 21° /12° 0 mm 5
Dec. 24 Sunny
Sunny
 20° /13° 0 mm 5
Dec. 25 Sunny
Sunny
 21° /12° 0 mm 5
Dec. 26 Sunny
Sunny
 23° /13° 0 mm 5
Dec. 27 Sunny
Sunny
 23° /14° 0 mm 5
Dec. 28 Sunny
Sunny
 24° /16° 0 mm 5
Dec. 29 Overcast
Overcast
 19° /9° 0 mm 5
Dec. 30 Light rain shower
Light rain shower
 17° /6° 4.8 mm 5
Dec. 31 Light rain shower
Light rain shower
 15° /7° 1.9 mm 4
Next
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 9°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Ontario during December?
In December, Ontario can expect light to moderate rainfall, totaling 23.4 mm across approximately 6 days. Occasional showers are possible, and planning ahead for them could be helpful.
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 6 rainy days in December with a total of 23.4 mm of rainfall.

UV exposure in Ontario during December

Stay informed about UV levels for safe outdoor activities throughout the month of December ☀️

Quick links

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Location coordinates Where is Ontario?

Get accurate weather forecasts for Ontario, located at latitude 34.063 and longitude -117.651. Stay updated with localized weather information tailored for Ontario.

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