May is one of the warmer months of the year in Halton Hills, with average highs near 19.2°C and lows around 6.6°C (mean 12.9°C). It is about average for rainfall, averaging 68 mm of rainfall and 72% relative humidity across the period.
May is one of the warmer months of the year in Halton Hills. Across 45 years of records, the warmest May in Halton Hills was 1998 — when the month averaged 16.4°C — while the coldest was 1997 at 8.4°C. Typical May days reach 19.2°C with nights near 6.6°C. The long-term trend is warming, about 0.2°C per decade.
May is about average for rainfall in Halton Hills, averaging 68 mm of rainfall. The wettest May on record was 2000 with 164 mm, while the driest was 2021 at 28 mm.
Relative humidity in Halton Hills during May averages 72%. The most humid May was 2011 at 85%, and the least humid was 2021 at 62%.
May receives about 5.5 kWh/m²/day of solar energy in Halton Hills. The sunniest May was 2023 at 6.3 kWh/m²/day, and the cloudiest was 1984 at 4.4.
Average wind speed in Halton Hills during May is 3 m/s. The windiest May was 1997 at 3.7 m/s, while the calmest was 1982 at 2.3 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 13.0°C | 12.8°C | 12.0°C | 13.7°C | 13.3°C | +0.3°C |
| Avg High | 19.3°C | 19.3°C | 18.2°C | 19.9°C | 19.7°C | +0.4°C |
| Avg Low | 6.7°C | 6.2°C | 5.9°C | 7.4°C | 7.0°C | +0.3°C |
| Avg Rain | 62 mm | 61 mm | 86 mm | 73 mm | 52 mm | -10 mm |
May temperatures in Halton Hills have risen by about 1.9°C between 1981–1985 and 2021–2025.
May has ranged from a record low of -4.2°C (1986) to a record high of 33°C (1988).
Rainfall in May is about average for rainfall, averaging 68 mm, with a wettest year of 164 mm.
A good time to visit Halton Hills
May is a good time to visit Halton Hills, with days averaging 19.2°C and nights around 6.6°C (mean 12.9°C, warmer than Halton Hills's yearly average) and moderate rainfall. July and August are marginally more temperate, but May still suits most travellers.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 18.3°C | 12.6°C | 6.9°C | 27.3°C | 1.1°C | 68 mm | 74% | 3.3 m/s | 5 |
| 2024 | 21.8°C | 15.5°C | 9.2°C | 28.5°C | 4.5°C | 72 mm | 73% | 2.5 m/s | 5.7 |
| 2023 | 19.8°C | 12.8°C | 5.9°C | 30.9°C | -0.3°C | 34 mm | 64% | 2.4 m/s | 6.3 |
| 2022 | 20.4°C | 14.1°C | 7.7°C | 30.9°C | 0.0°C | 62 mm | 74% | 2.8 m/s | 5.7 |
| 2021 | 20.1°C | 13.3°C | 6.5°C | 31.0°C | -2.6°C | 28 mm | 62% | 2.8 m/s | 5.7 |
| 2020 | 17.5°C | 11.5°C | 5.5°C | 30.7°C | -4.0°C | 46 mm | 71% | 3.1 m/s | 5.4 |
| 2019 | 17.5°C | 11.2°C | 5.0°C | 26.1°C | -0.5°C | 72 mm | 82% | 2.9 m/s | 4.6 |
| 2018 | 22.8°C | 15.5°C | 8.3°C | 30.9°C | 0.8°C | 65 mm | 73% | 2.8 m/s | 6.1 |
| 2017 | 16.3°C | 11.3°C | 6.2°C | 27.1°C | -1.3°C | 120 mm | 81% | 3.2 m/s | 5 |
| 2016 | 19.0°C | 12.9°C | 6.8°C | 29.9°C | -0.8°C | 52 mm | 74% | 2.5 m/s | 6 |
| 2015 | 22.3°C | 15.3°C | 8.2°C | 28.8°C | -1.2°C | 60 mm | 69% | 2.9 m/s | 5.8 |
| 2014 | 18.8°C | 12.9°C | 7.0°C | 26.5°C | 0.1°C | 62 mm | 78% | 2.8 m/s | 5.4 |
| 2013 | 20.1°C | 13.8°C | 7.5°C | 28.2°C | -0.8°C | 86 mm | 75% | 2.9 m/s | 6.1 |
| 2012 | 23.0°C | 16.1°C | 9.1°C | 32.9°C | 1.9°C | 39 mm | 67% | 2.5 m/s | 6 |
| 2011 | 17.7°C | 12.6°C | 7.5°C | 28.7°C | 1.3°C | 110 mm | 85% | 2.8 m/s | 4.5 |
| 2010 | 21.2°C | 14.9°C | 8.6°C | 31.8°C | -1.5°C | 68 mm | 70% | 3 m/s | 5.7 |
| 2009 | 18.9°C | 12.0°C | 5.1°C | 25.9°C | -1.8°C | 74 mm | 73% | 3.1 m/s | 6.1 |
| 2008 | 17.0°C | 10.9°C | 4.7°C | 24.4°C | -0.4°C | 69 mm | 73% | 3.1 m/s | 5.3 |
| 2007 | 20.7°C | 13.8°C | 6.9°C | 30.6°C | 0.2°C | 44 mm | 66% | 2.4 m/s | 6.2 |
| 2006 | 20.1°C | 13.9°C | 7.7°C | 33.0°C | 1.1°C | 51 mm | 71% | 2.8 m/s | 5.5 |
| 2005 | 17.3°C | 11.1°C | 5.0°C | 25.4°C | -2.7°C | 28 mm | 70% | 2.5 m/s | 5.9 |
| 2004 | 18.2°C | 12.1°C | 6.1°C | 26.4°C | -4.0°C | 116 mm | 82% | 2.9 m/s | 4.9 |
| 2003 | 16.3°C | 10.8°C | 5.3°C | 22.9°C | 0.0°C | 128 mm | 81% | 3.1 m/s | 4.8 |
| 2002 | 15.1°C | 9.2°C | 3.3°C | 24.4°C | -2.7°C | 83 mm | 78% | 3.4 m/s | 5.1 |
| 2001 | 19.5°C | 13.4°C | 7.3°C | 26.5°C | 0.4°C | 104 mm | 75% | 2.8 m/s | 5.6 |
| 2000 🌧️ | 18.7°C | 12.9°C | 7.1°C | 26.4°C | 2.5°C | 164 mm | 80% | 3.2 m/s | 4.9 |
| 1999 | 21.3°C | 14.4°C | 7.5°C | 31.2°C | 2.1°C | 52 mm | 66% | 2.9 m/s | 6.1 |
| 1998 🔥 | 23.0°C | 16.4°C | 9.8°C | 29.8°C | 3.9°C | 31 mm | 68% | 2.8 m/s | 5.8 |
| 1997 ❄️ | 14.5°C | 8.4°C | 2.3°C | 22.0°C | -2.7°C | 92 mm | 74% | 3.7 m/s | 4.9 |
| 1996 | 17.4°C | 11.0°C | 4.6°C | 27.2°C | -2.7°C | 59 mm | 69% | 2.9 m/s | 5.6 |
| 1995 | 19.7°C | 13.0°C | 6.2°C | 28.0°C | -0.5°C | 50 mm | 64% | 3.1 m/s | 5.4 |
| 1994 | 18.4°C | 11.7°C | 5.0°C | 30.2°C | -0.7°C | 75 mm | 68% | 3.2 m/s | 5.3 |
| 1993 | 19.1°C | 12.6°C | 6.1°C | 27.3°C | 1.7°C | 57 mm | 67% | 3.2 m/s | 5.1 |
| 1992 | 19.8°C | 12.7°C | 5.6°C | 28.9°C | -0.2°C | 41 mm | 65% | 2.6 m/s | 6.1 |
| 1991 | 22.2°C | 16.0°C | 9.9°C | 29.3°C | 0.1°C | 75 mm | 74% | 2.9 m/s | 5.5 |
| 1990 | 17.6°C | 11.5°C | 5.4°C | 24.7°C | -0.5°C | 83 mm | 68% | 3.4 m/s | 5 |
| 1989 | 19.5°C | 13.4°C | 7.3°C | 28.7°C | 0.6°C | 35 mm | 67% | 3.3 m/s | 4.9 |
| 1988 | 21.8°C | 14.8°C | 7.7°C | 33.0°C | 1.0°C | 46 mm | 63% | 3 m/s | 5.8 |
| 1987 | 22.4°C | 15.3°C | 8.2°C | 32.5°C | -0.5°C | 37 mm | 63% | 3.2 m/s | 5.9 |
| 1986 | 20.1°C | 14.1°C | 8.1°C | 29.3°C | -4.2°C | 70 mm | 75% | 3.2 m/s | 5.4 |
| 1985 | 19.3°C | 13.1°C | 6.9°C | 25.9°C | 1.3°C | 68 mm | 76% | 3.2 m/s | 5.7 |
| 1984 | 15.2°C | 9.5°C | 3.8°C | 24.4°C | -1.4°C | 58 mm | 79% | 3.4 m/s | 4.4 |
| 1983 | 15.4°C | 9.3°C | 3.2°C | 21.3°C | -3.2°C | 117 mm | 80% | 3.3 m/s | — |
| 1982 | 20.7°C | 14.6°C | 8.6°C | 26.2°C | 2.5°C | 66 mm | 77% | 2.3 m/s | — |
| 1981 | 18.9°C | 12.5°C | 6.2°C | 27.5°C | -0.9°C | 58 mm | 67% | 2.7 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 19.2°C with lows near 6.6°C (mean 12.9°C), based on 45 years of NASA POWER data.
May averages 68 mm of rainfall in Halton Hills, about average for rainfall. The wettest on record was 164 mm in 2000.
The hottest May reached 33°C in 1988. The coldest dipped to -4.2°C in 1986.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 1.9°C. Daytime highs moved from 17.9°C to 20.1°C and overnight lows from 5.7°C to 7.2°C over the same span.
May is one of the warmer months of the year in Halton Hills and about average for rainfall, so plan for around 19.2°C daytime highs and 6.6°C at night.
Not quite — May is the 8th coolest month in Halton Hills, averaging 12.9°C.
For May in Halton Hills, pack warm layers and a jacket for chilly mornings, with typical highs of 19.2°C and lows of 6.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 72% — moderately humid.
Average wind speed in May is 3 m/s. The windiest May on record averaged 3.7 m/s (1997).
The wettest May on record was 2000 with 164 mm. On average, May sees 68 mm.
All figures are derived from NASA POWER (Prediction Of Worldwide Energy Resources), based on MERRA-2 satellite reanalysis, covering 1981–2025.
Explore how the weather in Halton Hills behaves each May, based on 45 years of NASA POWER climate data from 1981 to 2025. This page breaks down average temperatures, rainfall, humidity, wind and solar radiation for May specifically, along with year-by-year records and how the month has changed over the decades.
