Weather on May 31
Ontario, CA
55 Years of Data
About This Date
May 31st in Ontario, CA typically brings warm spring weather, with average highs around 82°F and lows near 56°F — a 26°F daily swing. Over 43 years of records, the warmest May 31st was in 2025 (80°F average), while the coldest was 1980 (55°F) — a 25°F range across recorded history. This date has historically been dry, with little recorded precipitation. The last decade has been 1.6°F cooler on this date compared to 20-30 years ago.
The last decade has been 1.6°F cooler on this date compared to 20-30 years ago.
Planning for May 31st in Ontario, CA? Stay hydrated and seek shade during peak afternoon hours.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2026 | 89° | 59° | 74° | — | — |
| 2025warmest | 96° | 64° | 80° | — | — |
| 2024 | 80° | 57° | 69° | — | — |
| 2023 | 63° | 56° | 59° | — | — |
| 2022 | 82° | 55° | 69° | — | — |
| 2021 | 86° | 60° | 73° | — | — |
| 2020 | 87° | 59° | 73° | — | — |
| 2019 | 83° | 60° | 71° | — | — |
| 2018 | 76° | 57° | 66° | — | — |
| 2017 | 72° | 61° | 66° | — | — |
| 2016 | 80° | 55° | 68° | — | — |
| 2015 | 83° | 57° | 70° | — | — |
| 2014 | 90° | 60° | 75° | — | — |
| 2013 | 89° | 61° | 75° | — | — |
| 2012 | 94° | 57° | 75° | — | — |
| 2011 | 82° | 53° | 68° | — | — |
| 2010 | 82° | 56° | 69° | — | — |
| 2009 | 76° | 60° | 68° | — | — |
| 2008 | 79° | 54° | 66° | — | — |
| 2007 | 80° | 53° | 67° | — | — |
| 2006 | 96° | 62° | 79° | — | — |
| 2005 | 83° | 56° | 69° | — | — |
| 2004 | 94° | 60° | 77° | — | — |
| 2003 | 85° | 59° | 72° | — | — |
| 2002 | 89° | 58° | 73° | — | — |
| 2001 | 94° | 60° | 77° | — | — |
| 2000 | 85° | 58° | 71° | — | — |
| 1999 | 80° | 53° | 67° | — | — |
| 1998 | 79° | 52° | 65° | — | — |
| 1984 | 89° | 58° | 73° | — | — |
| 1983 | 65° | 56° | 60° | — | — |
| 1982 | 74° | 45° | 59° | — | — |
| 1981 | 85° | 60° | 72° | — | — |
| 1980coldest | 60° | 50° | 55° | — | — |
| 1979 | 76° | 50° | 63° | — | — |
| 1978 | 81° | 49° | 65° | — | — |
| 1977 | 91° | 55° | 73° | — | — |
| 1976 | 79° | 45° | 62° | — | — |
| 1975 | 83° | 51° | 67° | — | — |
| 1974 | 70° | 51° | 60° | — | — |
| 1973 | 73° | 55° | 64° | — | — |
| 1972 | 91° | 61° | 76° | — | — |
| 1971 | 65° | 48° | 56° | — | — |
Ontario, CA Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
Ontario, CA Monthly Precipitation
Average rainfall per month, in inches.
Ontario, CA Daily Temperature Calendar
Average daily high temperature for every day of the year. Each cell is the climatological mean for that calendar day across 55 years of NOAA data.
Best Time to Visit Ontario, CA
Most pleasant months in Ontario, CA: January, February, March, April, May, October, November, December.
What to expect on May 31st
This page shows what actually happened each year. For the odds — typical high and low, and how often it stays dry — see the climatological outlook for this date.
May 31st outlook →