Ontario Weather in May
Average highs run from 78°F on May 1 to 82°F on May 31, and lows from 54°F to 57°F. Normal precipitation for the month is 0.30 in over about 2 wet days.
May day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
May at a glance
- Average high
- 80°F
- Average low
- 56°F
- Precipitation
- 0.30 in
- Record high
- 103°FMay 3, 2004
- Record low
- 42°FMay 1, 1999
- Chance of a freeze
- 0%
- Days of 90°F or more
- 5.0
- Daylight
- 13 h 34 min to 14 h 15 min
- Cloud cover
- 26%
- Humidity
- 56%
- Dew point
- 44°F
- Wind
- 6.3 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation.
| Date | Normal high | Normal low | Record high | Record low | Chance wet |
|---|---|---|---|---|---|
| May 1 | 78°F | 54°F | 94°F 2004 | 42°F 1999 | 9% |
| May 2 | 78°F | 54°F | 101°F 2004 | 46°F 1999 | 9% |
| May 3 | 78°F | 54°F | 103°F 2004 | 48°F 2023 | 8% |
| May 4 | 78°F | 54°F | 95°F 2004 | 46°F 2001 | 8% |
| May 5 | 79°F | 54°F | 97°F 2018 | 45°F 1999 | 8% |
| May 6 | 79°F | 54°F | 98°F 2020 | 43°F 2016 | 8% |
| May 7 | 79°F | 55°F | 99°F 2020 | 46°F 2017 | 8% |
| May 8 | 79°F | 55°F | 98°F 2007 | 44°F 2017 | 7% |
| May 9 | 79°F | 55°F | 100°F 2025 | 49°F 2003 | 7% |
| May 10 | 79°F | 55°F | 103°F 2025 | 46°F 2003 | 7% |
| May 11 | 79°F | 55°F | 97°F 2013 | 46°F 2022 | 7% |
| May 12 | 79°F | 55°F | 103°F 2013 | 47°F 2000 | 7% |
| May 13 | 79°F | 55°F | 103°F 2013 | 49°F 2000 | 6% |
| May 14 | 80°F | 56°F | 98°F 2014 | 50°F 2000 | 6% |
| May 15 | 80°F | 56°F | 102°F 2014 | 49°F 2011 | 6% |
| May 16 | 80°F | 56°F | 100°F 2008 | 46°F 2011 | 6% |
| May 17 | 80°F | 56°F | 102°F 2008 | 45°F 2006 | 6% |
| May 18 | 80°F | 56°F | 101°F 2008 | 49°F 2011 | 6% |
| May 19 | 80°F | 56°F | 97°F 2008 | 46°F 2011 | 5% |
| May 20 | 80°F | 56°F | 98°F 2000 | 51°F 2002 | 5% |
| May 21 | 80°F | 56°F | 101°F 2000 | 47°F 2002 | 5% |
| May 22 | 80°F | 56°F | 96°F 2005 | 48°F 2002 | 5% |
| May 23 | 81°F | 57°F | 97°F 2001 | 50°F 2010 | 5% |
| May 24 | 81°F | 57°F | 97°F 2021 | 48°F 2010 | 4% |
| May 25 | 81°F | 57°F | 92°F 2020 | 48°F 2010 | 4% |
| May 26 | 81°F | 57°F | 95°F 2020 | 49°F 2012 | 4% |
| May 27 | 81°F | 57°F | 99°F 2000 | 46°F 1998 | 4% |
| May 28 | 81°F | 57°F | 103°F 2003 | 50°F 1998 | 4% |
| May 29 | 82°F | 57°F | 99°F 2002 | 49°F 2010 | 3% |
| May 30 | 82°F | 57°F | 100°F 2025 | 49°F 1998 | 3% |
| May 31 | 82°F | 57°F | 96°F 2006 | 52°F 1998 | 3% |
Chance of rain
- Chance of a wet day
Sunrise and sunset
Times for 2026, local time (PDT).
- May 1
- sunrise 6:01 AM, sunset 7:35 PM
- May 31
- sunrise 5:41 AM, sunset 7:56 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USW00003102 (Ontario Intl AP), public domain. Records: NOAA GHCN-Daily, station USW00003102, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.