Ontario (CA)
May
Weather in Ontario, California for May 2026
Your guide to Ontario weather in May - trends and predictions
In general, the average temperature in Ontario at the beginning of May is 20 °F. As the month progressed, temperatures tended to significantly warm up, reaching an average of 24.7 °F by the end of May.
Precipitation in Ontario during May is a rare event, with an average of fewer than 2 rainy days.
New! Chat with our AI weatherman - it’s amazing and free.
Temperatures
Rain 🌧️
More
30
Dry days
1
Rainy days
0
Snow days
24°/11°
Temperatures
17 km/h
Avg max wind
53 %
Avg humidity
Ontario Weather May
Move between months or click on a day
Temperatures trend during May in Ontario
See the weather trend as well as the moving average line
May weather in Ontario day by day
Click on a date for more information
| Date | Weather | Temperatures | Rain | UV | More |
|---|---|---|---|---|---|
| May 1 |  Sunny | 22° /11° | 0 mm | 6 | |
| May 2 | Sunny | 23° /12° | 0 mm | 7 | |
| May 3 | Sunny | 21° /10° | 0 mm | 5 | |
| May 4 |  Partly cloudy | 17° /8° | 0.1 mm | 5 | |
| May 5 |  Patchy rain possible | 15° /9° | 2.9 mm | 4 | |
| May 6 | Sunny | 19° /8° | 0 mm | 5 | |
| May 7 | Sunny | 23° /11° | 0 mm | 6 | |
| May 8 | Sunny | 26° /10° | 0 mm | 7 | |
| May 9 | Sunny | 30° /13° | 0 mm | 8 | |
| May 10 | Sunny | 31° /15° | 0 mm | 8 | |
| May 11 | Sunny | 29° /15° | 0 mm | 7 | |
| May 12 | Sunny | 24° /12° | 0 mm | 7 | |
| May 13 |  Overcast | 20° /11° | 0 mm | 5 | |
| May 14 | Sunny | 23° /9° | 0 mm | 6 | |
| May 15 | Sunny | 24° /10° | 0 mm | 6 | |
| May 16 | Sunny | 22° /10° | 0 mm | 5 | |
| May 17 | Partly cloudy | 19° /10° | 0 mm | 5 | |
| May 18 | Sunny | 22° /10° | 0 mm | 6 | |
| May 19 | Sunny | 26° /10° | 0 mm | 7 | |
| May 20 | Overcast | 30° /16° | 0 mm | 7 | |
| May 21 |  Cloudy | 30° /15° | 0 mm | 7 | |
| May 22 | Sunny | 28° /13° | 0 mm | 7 | |
| May 23 | Sunny | 24° /12° | 0 mm | 7 | |
| May 24 | Partly cloudy | 21° /11° | 0.1 mm | 5 | |
| May 25 | Sunny | 21° /9° | 0 mm | 5 | |
| May 26 | Partly cloudy | 22° /11° | 0 mm | 6 | |
| May 27 | Sunny | 26° /11° | 0 mm | 7 | |
| May 28 | Sunny | 25° /12° | 0 mm | 7 | |
| May 29 | Sunny | 26° /11° | 0 mm | 7 | |
| May 30 | Sunny | 28° /14° | 0.2 mm | 7 | |
| May 31 | Patchy rain possible | 25° /14° | 0.1 mm | 6 | |
| Next | |||||
Important Notice
Our weather forecast for Ontario in May 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.
Change Month
Ontario in May - FAQ
What are the expected maximum and minimum temperatures in Ontario during May?
Enjoy moderate daytime temperatures of up to 24° and cooler nights around 11°. Ideal for a range of outdoor activities, from hiking to city tours.
How much rainfall should be expected in Ontario during May?
Rainfall in Ontario during May is rare to nonexistent, with the total expected rainfall being less than 10 mm and approximately 1 days seeing any precipitation. Planning without the concern for rain is generally straightforward during this very dry period.
What are the typical wind conditions in Ontario during May?
The average wind speed in Ontario during May is 17 km/h, suggesting breezy to windy conditions, depending on your activities.
May rainfall patterns in Ontario
Explore the daily rainfall trends and prepare for Ontarios May weather 💧
UV exposure in Ontario during May
Stay informed about UV levels for safe outdoor activities throughout the month of May ☀️
Quick links
More Ontario weather pages
You are here
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.
Found a mistake?
We appreciate your attention to details. Tell us here.