May is one of the warmer months of the year in Cornwall, with average highs near 18.8°C and lows around 7.2°C (mean 13°C). It is about average for rainfall, averaging 83 mm of rainfall and 77% relative humidity across the period.
May is one of the warmer months of the year in Cornwall. Across 45 years of records, the warmest May in Cornwall was 2024 — when the month averaged 15.9°C — while the coldest was 1997 at 9.7°C. Typical May days reach 18.8°C with nights near 7.2°C. The long-term trend is warming, about 0.3°C per decade.
May is about average for rainfall in Cornwall, averaging 83 mm of rainfall. The wettest May on record was 2017 with 161 mm, while the driest was 2021 at 21 mm.
Relative humidity in Cornwall during May averages 77%. The most humid May was 2011 at 84%, and the least humid was 2021 at 68%.
May receives about 5.3 kWh/m²/day of solar energy in Cornwall. The sunniest May was 2023 at 6.3 kWh/m²/day, and the cloudiest was 1984 at 4.1.
Average wind speed in Cornwall during May is 0.5 m/s. The windiest Mays were 2019, 2020 and 2023, among others at 0.5 m/s, while the calmest were 2022, 2024 and 2025, among others at 0.4 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.7°C | 12.5°C | 12.4°C | 13.9°C | 13.7°C | +1°C |
| Avg High | 18.3°C | 18.4°C | 18.2°C | 19.7°C | 19.7°C | +1.4°C |
| Avg Low | 7.0°C | 6.7°C | 6.7°C | 7.9°C | 7.7°C | +0.7°C |
| Avg Rain | 87 mm | 76 mm | 101 mm | 87 mm | 54 mm | -33 mm |
May temperatures in Cornwall have risen by about 2°C between 1981–1985 and 2021–2025.
May has ranged from a record low of -3.8°C (2020) to a record high of 32.6°C (2012).
Rainfall in May is about average for rainfall, averaging 83 mm, with a wettest year of 161 mm.
A good time to visit Cornwall
May is a good time to visit Cornwall, with days averaging 18.8°C and nights around 7.2°C (mean 13°C, warmer than Cornwall's yearly average) and higher 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 | 18.8°C | 13.4°C | 8.0°C | 27.2°C | 2.8°C | 71 mm | 79% | 0.4 m/s | 4.6 |
| 2024 🔥 | 21.1°C | 15.9°C | 10.7°C | 30.3°C | 5.3°C | 70 mm | 78% | 0.4 m/s | 5.2 |
| 2023 | 19.2°C | 12.5°C | 5.9°C | 30.8°C | -0.6°C | 47 mm | 71% | 0.5 m/s | 6.3 |
| 2022 | 21.7°C | 15.1°C | 8.5°C | 30.2°C | 0.3°C | 80 mm | 74% | 0.4 m/s | 5.8 |
| 2021 | 19.6°C | 13.5°C | 7.3°C | 31.2°C | -1.4°C | 21 mm | 68% | 0.4 m/s | 5.8 |
| 2020 | 17.9°C | 11.8°C | 5.8°C | 31.3°C | -3.8°C | 38 mm | 73% | 0.5 m/s | 6 |
| 2019 | 16.4°C | 11.1°C | 5.8°C | 22.6°C | -0.6°C | 95 mm | 80% | 0.5 m/s | 4.6 |
| 2018 | 21.1°C | 14.4°C | 7.8°C | 30.0°C | 1.6°C | 56 mm | 77% | 0.5 m/s | 5.9 |
| 2017 🌧️ | 17.3°C | 12.3°C | 7.4°C | 27.8°C | -3.1°C | 161 mm | 81% | 0.5 m/s | 4.6 |
| 2016 | 19.3°C | 13.1°C | 6.8°C | 29.3°C | -2.9°C | 32 mm | 76% | 0.5 m/s | 5.8 |
| 2015 | 21.9°C | 15.4°C | 8.9°C | 29.0°C | -1.7°C | 61 mm | 72% | 0.5 m/s | 5.7 |
| 2014 | 19.2°C | 13.4°C | 7.6°C | 27.7°C | 0.5°C | 100 mm | 79% | 0.5 m/s | 5.5 |
| 2013 | 20.7°C | 14.5°C | 8.2°C | 29.6°C | 2.1°C | 95 mm | 74% | 0.5 m/s | 5.5 |
| 2012 | 21.7°C | 15.7°C | 9.7°C | 32.6°C | 3.4°C | 78 mm | 77% | 0.4 m/s | 5.6 |
| 2011 | 18.8°C | 13.8°C | 8.7°C | 28.7°C | 1.0°C | 141 mm | 84% | 0.4 m/s | 4.5 |
| 2010 | 21.0°C | 14.8°C | 8.6°C | 31.1°C | -2.1°C | 47 mm | 75% | 0.4 m/s | 5.8 |
| 2009 | 17.8°C | 12.2°C | 6.5°C | 24.8°C | 1.4°C | 105 mm | 76% | 0.5 m/s | 5.2 |
| 2008 | 17.6°C | 11.6°C | 5.6°C | 23.4°C | -0.2°C | 74 mm | 75% | 0.5 m/s | 5.8 |
| 2007 | 19.2°C | 12.6°C | 6.0°C | 28.0°C | -1.0°C | 67 mm | 75% | 0.5 m/s | 6 |
| 2006 | 18.7°C | 13.5°C | 8.4°C | 29.0°C | -1.4°C | 103 mm | 81% | 0.5 m/s | 4.9 |
| 2005 | 16.5°C | 11.0°C | 5.5°C | 26.5°C | -2.5°C | 36 mm | 77% | 0.4 m/s | 5.2 |
| 2004 | 19.0°C | 13.2°C | 7.3°C | 28.3°C | -1.8°C | 120 mm | 80% | 0.5 m/s | 5.2 |
| 2003 | 18.4°C | 12.6°C | 6.8°C | 26.5°C | -0.9°C | 154 mm | 79% | 0.4 m/s | 5 |
| 2002 | 16.0°C | 10.3°C | 4.7°C | 26.2°C | -1.2°C | 120 mm | 76% | 0.5 m/s | 4.9 |
| 2001 | 20.2°C | 14.3°C | 8.4°C | 26.6°C | 0.9°C | 81 mm | 78% | 0.4 m/s | 5.2 |
| 2000 | 18.5°C | 12.9°C | 7.3°C | 25.8°C | -0.5°C | 146 mm | 81% | 0.5 m/s | 4.7 |
| 1999 | 21.5°C | 14.9°C | 8.2°C | 28.9°C | 0.5°C | 51 mm | 74% | 0.5 m/s | 6 |
| 1998 | 21.8°C | 15.8°C | 9.8°C | 28.2°C | 4.2°C | 66 mm | 77% | 0.4 m/s | 5.8 |
| 1997 ❄️ | 15.1°C | 9.7°C | 4.3°C | 22.8°C | -3.0°C | 74 mm | 78% | 0.5 m/s | 4.9 |
| 1996 | 16.8°C | 11.0°C | 5.1°C | 25.0°C | -0.4°C | 97 mm | 76% | 0.4 m/s | 5.8 |
| 1995 | 18.1°C | 12.3°C | 6.5°C | 23.5°C | -3.4°C | 65 mm | 75% | 0.5 m/s | 5 |
| 1994 | 17.2°C | 11.4°C | 5.5°C | 26.1°C | -0.8°C | 97 mm | 79% | 0.5 m/s | 5.3 |
| 1993 | 18.2°C | 12.6°C | 7.0°C | 27.5°C | 2.5°C | 72 mm | 79% | 0.5 m/s | 5 |
| 1992 | 18.8°C | 12.3°C | 5.8°C | 26.4°C | 0.7°C | 78 mm | 75% | 0.5 m/s | 6.1 |
| 1991 | 20.1°C | 14.5°C | 9.0°C | 26.6°C | 0.0°C | 83 mm | 79% | 0.5 m/s | 5.4 |
| 1990 | 16.1°C | 10.9°C | 5.7°C | 23.7°C | 0.0°C | 79 mm | 79% | 0.5 m/s | 5 |
| 1989 | 18.5°C | 13.3°C | 8.1°C | 27.9°C | 0.7°C | 106 mm | 80% | 0.5 m/s | 4.5 |
| 1988 | 19.4°C | 13.6°C | 7.8°C | 26.6°C | 0.8°C | 50 mm | 77% | 0.4 m/s | 5.4 |
| 1987 | 18.6°C | 12.7°C | 6.9°C | 28.7°C | -1.7°C | 60 mm | 77% | 0.5 m/s | 5.2 |
| 1986 | 19.2°C | 13.8°C | 8.4°C | 26.4°C | -2.9°C | 104 mm | 80% | 0.5 m/s | 5 |
| 1985 | 18.5°C | 12.6°C | 6.6°C | 26.6°C | -1.2°C | 78 mm | 75% | 0.5 m/s | 5.6 |
| 1984 | 15.7°C | 10.8°C | 5.8°C | 25.5°C | -0.2°C | 115 mm | 80% | 0.5 m/s | 4.1 |
| 1983 | 16.1°C | 10.6°C | 5.2°C | 22.0°C | -2.2°C | 110 mm | 81% | 0.5 m/s | — |
| 1982 | 20.0°C | 14.0°C | 8.0°C | 26.0°C | 3.5°C | 61 mm | 79% | 0.4 m/s | — |
| 1981 | 18.5°C | 12.5°C | 6.5°C | 25.4°C | -1.7°C | 102 mm | 77% | 0.4 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 18.8°C with lows near 7.2°C (mean 13°C), based on 45 years of NASA POWER data.
May averages 83 mm of rainfall in Cornwall, about average for rainfall. The wettest on record was 161 mm in 2017.
The hottest May reached 32.6°C in 2012. The coldest dipped to -3.8°C in 2020.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 2°C. Daytime highs moved from 17.8°C to 20.1°C and overnight lows from 6.4°C to 8.1°C over the same span.
May is one of the warmer months of the year in Cornwall and about average for rainfall, so plan for around 18.8°C daytime highs and 7.2°C at night.
Not quite — May is the 8th coolest month in Cornwall, averaging 13°C.
For May in Cornwall, pack warm layers and a jacket for chilly mornings, with typical highs of 18.8°C and lows of 7.2°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 77% — quite humid.
Average wind speed in May is 0.5 m/s. The windiest May on record averaged 0.5 m/s (1983).
The wettest May on record was 2017 with 161 mm. On average, May sees 83 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 Cornwall 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.
