May is one of the warmer months of the year in Round Lake, with average highs near 19.3°C and lows around 8°C (mean 13.7°C). It is a relatively wet time of year, averaging 101 mm of rainfall and 76% relative humidity across the period.
May is one of the warmer months of the year in Round Lake. Across 45 years of records, the warmest May in Round Lake was 1991 — when the month averaged 16.8°C — while the coldest was 1997 at 10.4°C. Typical May days reach 19.3°C with nights near 8°C. The long-term trend is warming, about 0.2°C per decade.
May is a relatively wet time of year in Round Lake, averaging 101 mm of rainfall. The wettest May on record was 2004 with 239 mm, while the driest was 1992 at 24 mm.
Relative humidity in Round Lake during May averages 76%. The most humid May was 1991 at 83%, and the least humid was 1988 at 69%.
May receives about 5.5 kWh/m²/day of solar energy in Round Lake. The sunniest May was 1988 at 6.8 kWh/m²/day, and the cloudiest was 1996 at 4.4.
Average wind speed in Round Lake during May is 3.4 m/s. The windiest May was 1997 at 4 m/s, while the calmest was 2018 at 2.8 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 13.5°C | 13.3°C | 13.4°C | 14.1°C | 14.1°C | +0.6°C |
| Avg High | 19.3°C | 18.9°C | 19.2°C | 19.6°C | 19.8°C | +0.5°C |
| Avg Low | 7.7°C | 7.7°C | 7.6°C | 8.5°C | 8.4°C | +0.7°C |
| Avg Rain | 85 mm | 97 mm | 114 mm | 117 mm | 85 mm | -1 mm |
May temperatures in Round Lake have risen by about 1.3°C between 1981–1985 and 2021–2025.
May has ranged from a record low of -4.6°C (1989) to a record high of 32.8°C (2018).
Rainfall in May is a relatively wet time of year, averaging 101 mm, with a wettest year of 239 mm.
A good time to visit Round Lake
May is a good time to visit Round Lake, with days averaging 19.3°C and nights around 8°C (mean 13.7°C, warmer than Round Lake's yearly average) and higher rainfall. August and July 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 | 18.8°C | 13.0°C | 7.3°C | 27.4°C | 2.3°C | 66 mm | 75% | 3.3 m/s | 5.7 |
| 2024 | 21.7°C | 15.7°C | 9.7°C | 27.6°C | 6.2°C | 120 mm | 76% | 3.3 m/s | 6 |
| 2023 | 20.3°C | 14.1°C | 7.8°C | 29.3°C | 0.1°C | 44 mm | 71% | 3 m/s | 6.3 |
| 2022 | 20.2°C | 15.1°C | 10.0°C | 29.1°C | 0.7°C | 82 mm | 79% | 3.5 m/s | 4.8 |
| 2021 | 19.9°C | 14.2°C | 8.5°C | 29.8°C | 0.2°C | 56 mm | 71% | 3.2 m/s | 5.4 |
| 2020 | 17.8°C | 12.6°C | 7.4°C | 28.0°C | -3.2°C | 140 mm | 80% | 3.2 m/s | 5.6 |
| 2019 | 17.8°C | 12.3°C | 6.8°C | 25.1°C | 1.4°C | 176 mm | 83% | 3.2 m/s | 4.9 |
| 2018 | 22.3°C | 16.5°C | 10.7°C | 32.8°C | 4.6°C | 159 mm | 80% | 2.8 m/s | 5.5 |
| 2017 | 17.6°C | 12.4°C | 7.2°C | 27.1°C | -0.5°C | 111 mm | 80% | 3.5 m/s | 5.5 |
| 2016 | 19.4°C | 13.8°C | 8.3°C | 27.1°C | -1.4°C | 88 mm | 76% | 3.2 m/s | 5.8 |
| 2015 | 20.3°C | 14.7°C | 9.1°C | 26.4°C | 1.6°C | 120 mm | 76% | 3.6 m/s | 5.1 |
| 2014 | 19.4°C | 13.5°C | 7.6°C | 27.5°C | 2.0°C | 111 mm | 77% | 3.2 m/s | 5.8 |
| 2013 | 19.3°C | 14.0°C | 8.7°C | 27.5°C | 0.3°C | 106 mm | 80% | 3.2 m/s | 5.4 |
| 2012 | 22.1°C | 16.1°C | 10.1°C | 32.5°C | 4.6°C | 74 mm | 73% | 3.3 m/s | 6 |
| 2011 | 17.8°C | 12.7°C | 7.6°C | 29.1°C | -0.8°C | 102 mm | 82% | 3.7 m/s | 5.1 |
| 2010 | 20.0°C | 14.6°C | 9.2°C | 29.8°C | -0.4°C | 123 mm | 77% | 3.3 m/s | 5.6 |
| 2009 | 19.1°C | 13.3°C | 7.5°C | 25.9°C | 0.5°C | 81 mm | 77% | 3.4 m/s | 5.7 |
| 2008 | 17.5°C | 11.5°C | 5.5°C | 24.9°C | 1.0°C | 82 mm | 77% | 3.6 m/s | 5.6 |
| 2007 | 21.4°C | 15.4°C | 9.3°C | 28.4°C | 3.8°C | 47 mm | 75% | 3.4 m/s | 6.1 |
| 2006 | 19.8°C | 14.5°C | 9.1°C | 30.3°C | 2.5°C | 111 mm | 78% | 3.2 m/s | 5.3 |
| 2005 | 18.8°C | 12.9°C | 7.1°C | 25.8°C | -1.3°C | 65 mm | 72% | 3.4 m/s | 5.5 |
| 2004 🌧️ | 19.8°C | 13.7°C | 7.6°C | 27.9°C | -0.4°C | 239 mm | 81% | 3.5 m/s | 4.9 |
| 2003 | 18.2°C | 12.4°C | 6.5°C | 25.7°C | 0.7°C | 122 mm | 75% | 3.8 m/s | 5.4 |
| 2002 | 17.1°C | 11.3°C | 5.5°C | 26.4°C | -0.9°C | 83 mm | 76% | 3.7 m/s | 5.5 |
| 2001 | 19.6°C | 14.2°C | 8.7°C | 28.1°C | 3.0°C | 123 mm | 76% | 3.4 m/s | 5.2 |
| 2000 | 21.0°C | 15.2°C | 9.3°C | 28.2°C | 2.8°C | 186 mm | 76% | 3.6 m/s | 4.5 |
| 1999 | 20.5°C | 15.0°C | 9.5°C | 27.8°C | 4.5°C | 102 mm | 77% | 3.7 m/s | 5.7 |
| 1998 | 21.8°C | 16.2°C | 10.6°C | 28.7°C | 6.0°C | 114 mm | 79% | 3.2 m/s | 5.9 |
| 1997 ❄️ | 16.3°C | 10.4°C | 4.5°C | 24.9°C | 0.0°C | 92 mm | 73% | 4 m/s | 5.5 |
| 1996 | 16.4°C | 11.0°C | 5.6°C | 28.4°C | -0.3°C | 181 mm | 79% | 3.4 m/s | 4.4 |
| 1995 | 18.1°C | 12.8°C | 7.4°C | 25.1°C | 2.2°C | 113 mm | 76% | 3.4 m/s | 5.1 |
| 1994 | 19.6°C | 13.0°C | 6.4°C | 28.4°C | 0.2°C | 25 mm | 69% | 3 m/s | 6.6 |
| 1993 | 18.9°C | 13.5°C | 8.1°C | 25.8°C | 1.3°C | 66 mm | 81% | 3.4 m/s | 5.1 |
| 1992 | 18.8°C | 12.5°C | 6.2°C | 26.1°C | -1.0°C | 24 mm | 71% | 3.1 m/s | 6.3 |
| 1991 🔥 | 21.5°C | 16.8°C | 12.2°C | 29.2°C | 1.8°C | 105 mm | 83% | 3.2 m/s | 5 |
| 1990 | 16.9°C | 11.5°C | 6.2°C | 23.4°C | -0.4°C | 151 mm | 76% | 3.7 m/s | 5.2 |
| 1989 | 19.1°C | 12.9°C | 6.7°C | 27.8°C | -4.6°C | 65 mm | 70% | 3.3 m/s | 5.7 |
| 1988 | 20.8°C | 14.1°C | 7.4°C | 29.9°C | 1.1°C | 26 mm | 69% | 3.2 m/s | 6.8 |
| 1987 | 21.4°C | 15.5°C | 9.5°C | 27.3°C | 1.0°C | 106 mm | 77% | 3.3 m/s | 5.8 |
| 1986 | 18.9°C | 13.6°C | 8.2°C | 28.3°C | -0.2°C | 98 mm | 79% | 3.3 m/s | 5.2 |
| 1985 | 20.4°C | 14.5°C | 8.7°C | 27.1°C | 1.7°C | 78 mm | 74% | 3.8 m/s | 6.1 |
| 1984 | 17.4°C | 11.7°C | 6.0°C | 24.5°C | 0.9°C | 114 mm | 76% | 3.6 m/s | 5.2 |
| 1983 | 16.3°C | 10.9°C | 5.5°C | 22.4°C | -1.8°C | 115 mm | 80% | 3.5 m/s | — |
| 1982 | 21.4°C | 16.2°C | 11.0°C | 26.3°C | 5.1°C | 102 mm | 81% | 3 m/s | — |
| 1981 | 17.9°C | 12.0°C | 6.1°C | 26.1°C | -0.6°C | 64 mm | 71% | 3.5 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 19.3°C with lows near 8°C (mean 13.7°C), based on 45 years of NASA POWER data.
May averages 101 mm of rainfall in Round Lake, a relatively wet time of year. The wettest on record was 239 mm in 2004.
The hottest May reached 32.8°C in 2018. The coldest dipped to -4.6°C in 1989.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 1.3°C. Daytime highs moved from 18.7°C to 20.2°C and overnight lows from 7.5°C to 8.7°C over the same span.
May is one of the warmer months of the year in Round Lake and a relatively wet time of year, so plan for around 19.3°C daytime highs and 8°C at night.
Not quite — May is the 8th coolest month in Round Lake, averaging 13.7°C.
For May in Round Lake, pack light layers you can adjust through the day, with typical highs of 19.3°C and lows of 8°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 76% — quite humid.
Average wind speed in May is 3.4 m/s. The windiest May on record averaged 4 m/s (1997).
The wettest May on record was 2004 with 239 mm. On average, May sees 101 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 Round Lake 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.
