May is one of the warmer months of the year in Saint John, with average highs near 15.3°C and lows around 4.9°C (mean 10.1°C). It is about average for rainfall, averaging 97 mm of rainfall and 82% relative humidity across the period.
May is one of the warmer months of the year in Saint John. Across 45 years of records, the warmest Mays in Saint John were 1989 and 1998 — when the month averaged 12.5°C — while the coldest were 1990 and 2019 at 8.2°C. Typical May days reach 15.3°C with nights near 4.9°C. The long-term May temperature trend is broadly flat.
May is about average for rainfall in Saint John, averaging 97 mm of rainfall. The wettest May on record was 1990 with 206 mm, while the driest was 1982 at 29 mm.
Relative humidity in Saint John during May averages 82%. The most humid May was 2011 at 88%, and the least humid was 2023 at 78%.
May receives about 5.1 kWh/m²/day of solar energy in Saint John. The sunniest May was 2018 at 6.4 kWh/m²/day, and the cloudiest were 2005 and 2011 at 4.
Average wind speed in Saint John during May is 0.5 m/s. The windiest Mays were 2005, 2020 and 2023, among others at 0.6 m/s, while the calmest were 2003, 2014 and 2024 at 0.4 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 10.2°C | 9.9°C | 9.9°C | 10.3°C | 10.6°C | +0.4°C |
| Avg High | 15.4°C | 15.2°C | 15.0°C | 15.4°C | 16.0°C | +0.6°C |
| Avg Low | 4.9°C | 4.6°C | 4.8°C | 5.3°C | 5.1°C | +0.2°C |
| Avg Rain | 107 mm | 99 mm | 97 mm | 105 mm | 62 mm | -45 mm |
May temperatures in Saint John have risen by about 1.1°C between 1981–1985 and 2021–2025.
May has ranged from a record low of -3.5°C (1987) to a record high of 28.7°C (1992).
Rainfall in May is about average for rainfall, averaging 97 mm, with a wettest year of 206 mm.
A good time to visit Saint John
May is a good time to visit Saint John, with days averaging 15.3°C and nights around 4.9°C (mean 10.1°C, warmer than Saint John'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 | 15.4°C | 10.6°C | 5.8°C | 24.7°C | -0.7°C | 93 mm | 83% | 0.5 m/s | 4.4 |
| 2024 | 16.9°C | 11.6°C | 6.2°C | 23.1°C | -0.2°C | 34 mm | 82% | 0.4 m/s | 5.3 |
| 2023 | 15.8°C | 10.1°C | 4.4°C | 27.6°C | -0.1°C | 61 mm | 78% | 0.6 m/s | 5.8 |
| 2022 | 17.2°C | 11.2°C | 5.2°C | 25.9°C | -2.4°C | 46 mm | 79% | 0.5 m/s | 6.1 |
| 2021 | 16.1°C | 10.7°C | 5.3°C | 22.8°C | 0.9°C | 55 mm | 79% | 0.5 m/s | 5.5 |
| 2020 | 14.8°C | 9.4°C | 4.0°C | 24.0°C | -0.4°C | 81 mm | 80% | 0.6 m/s | 5.9 |
| 2019 | 13.1°C | 8.2°C | 3.3°C | 20.6°C | -1.7°C | 101 mm | 82% | 0.5 m/s | 4.8 |
| 2018 | 16.7°C | 10.6°C | 4.6°C | 23.1°C | -0.8°C | 72 mm | 80% | 0.5 m/s | 6.4 |
| 2017 | 14.6°C | 9.7°C | 4.9°C | 27.0°C | 0.9°C | 171 mm | 84% | 0.5 m/s | 4.6 |
| 2016 | 15.5°C | 10.4°C | 5.4°C | 23.6°C | 0.7°C | 69 mm | 83% | 0.5 m/s | 5 |
| 2015 | 16.3°C | 10.9°C | 5.5°C | 23.0°C | -0.9°C | 100 mm | 82% | 0.5 m/s | 5.4 |
| 2014 | 14.2°C | 9.6°C | 4.9°C | 19.5°C | 1.1°C | 92 mm | 84% | 0.4 m/s | 4.8 |
| 2013 | 15.4°C | 10.4°C | 5.5°C | 26.4°C | -0.6°C | 135 mm | 85% | 0.5 m/s | 5 |
| 2012 | 16.6°C | 11.5°C | 6.4°C | 25.0°C | 0.2°C | 103 mm | 83% | 0.5 m/s | 4.8 |
| 2011 | 14.8°C | 10.5°C | 6.2°C | 23.7°C | 0.2°C | 154 mm | 88% | 0.5 m/s | 4 |
| 2010 | 16.5°C | 11.5°C | 6.4°C | 25.6°C | 0.5°C | 56 mm | 79% | 0.5 m/s | 5.8 |
| 2009 | 15.4°C | 10.6°C | 5.8°C | 23.8°C | 2.4°C | 101 mm | 83% | 0.5 m/s | 5 |
| 2008 | 14.8°C | 9.8°C | 4.7°C | 20.8°C | -1.4°C | 59 mm | 80% | 0.5 m/s | 5.6 |
| 2007 | 15.0°C | 9.7°C | 4.3°C | 27.2°C | -0.1°C | 89 mm | 82% | 0.5 m/s | 5.2 |
| 2006 | 17.0°C | 11.8°C | 6.6°C | 25.2°C | 1.3°C | 108 mm | 83% | 0.5 m/s | 4.8 |
| 2005 | 12.3°C | 8.3°C | 4.2°C | 19.3°C | -1.2°C | 185 mm | 85% | 0.6 m/s | 4 |
| 2004 | 14.8°C | 9.5°C | 4.1°C | 19.3°C | -1.1°C | 65 mm | 81% | 0.5 m/s | 4.9 |
| 2003 | 14.8°C | 9.6°C | 4.4°C | 26.5°C | -2.4°C | 96 mm | 82% | 0.4 m/s | 4.7 |
| 2002 | 14.3°C | 9.2°C | 4.2°C | 21.3°C | 0.2°C | 83 mm | 79% | 0.6 m/s | 5.4 |
| 2001 | 17.1°C | 11.1°C | 5.1°C | 24.0°C | -0.5°C | 91 mm | 81% | 0.5 m/s | 5.6 |
| 2000 | 14.1°C | 9.2°C | 4.3°C | 19.2°C | -0.9°C | 91 mm | 81% | 0.5 m/s | 5.1 |
| 1999 | 18.4°C | 12.4°C | 6.4°C | 23.4°C | 0.0°C | 62 mm | 80% | 0.5 m/s | 6 |
| 1998 | 18.3°C | 12.5°C | 6.6°C | 24.3°C | 1.7°C | 69 mm | 82% | 0.5 m/s | 5.4 |
| 1997 | 13.2°C | 8.5°C | 3.9°C | 20.7°C | -0.8°C | 103 mm | 83% | 0.5 m/s | 4.8 |
| 1996 | 13.7°C | 8.7°C | 3.6°C | 22.3°C | -1.9°C | 103 mm | 81% | 0.5 m/s | 5 |
| 1995 | 14.7°C | 9.5°C | 4.3°C | 19.8°C | -1.4°C | 73 mm | 82% | 0.5 m/s | 4.8 |
| 1994 | 13.6°C | 8.9°C | 4.1°C | 21.2°C | 0.1°C | 159 mm | 83% | 0.5 m/s | 4.9 |
| 1993 | 15.2°C | 10.0°C | 4.9°C | 19.9°C | -1.1°C | 83 mm | 83% | 0.5 m/s | 4.8 |
| 1992 | 15.7°C | 9.4°C | 3.0°C | 28.7°C | -2.2°C | 35 mm | 79% | 0.5 m/s | 6.1 |
| 1991 | 16.7°C | 11.1°C | 5.5°C | 25.1°C | 0.4°C | 96 mm | 80% | 0.5 m/s | 5.4 |
| 1990 ❄️ 🌧️ | 12.9°C | 8.2°C | 3.5°C | 21.8°C | -0.3°C | 206 mm | 83% | 0.5 m/s | 4.8 |
| 1989 🔥 | 17.5°C | 12.5°C | 7.4°C | 22.9°C | 3.5°C | 133 mm | 85% | 0.5 m/s | 4.4 |
| 1988 | 16.0°C | 10.5°C | 5.1°C | 21.1°C | -0.7°C | 91 mm | 82% | 0.5 m/s | 5.1 |
| 1987 | 15.9°C | 10.1°C | 4.3°C | 25.1°C | -3.5°C | 70 mm | 78% | 0.5 m/s | 5.7 |
| 1986 | 15.5°C | 10.0°C | 4.4°C | 21.9°C | -3.2°C | 73 mm | 80% | 0.5 m/s | 5.2 |
| 1985 | 14.5°C | 9.1°C | 3.8°C | 21.7°C | -2.6°C | 146 mm | 82% | 0.5 m/s | 5.5 |
| 1984 | 14.4°C | 9.7°C | 5.0°C | 22.0°C | 1.0°C | 136 mm | 85% | 0.5 m/s | 4.3 |
| 1983 | 13.9°C | 9.6°C | 5.3°C | 19.9°C | -0.6°C | 169 mm | 85% | 0.5 m/s | — |
| 1982 | 15.2°C | 9.5°C | 3.7°C | 24.0°C | -0.9°C | 29 mm | 80% | 0.5 m/s | — |
| 1981 | 15.9°C | 10.7°C | 5.5°C | 23.2°C | -1.3°C | 117 mm | 83% | 0.5 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 15.3°C with lows near 4.9°C (mean 10.1°C), based on 45 years of NASA POWER data.
May averages 97 mm of rainfall in Saint John, about average for rainfall. The wettest on record was 206 mm in 1990.
The hottest May reached 28.7°C in 1992. The coldest dipped to -3.5°C in 1987.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 1.1°C. Daytime highs moved from 14.8°C to 16.3°C and overnight lows from 4.7°C to 5.4°C over the same span.
May is one of the warmer months of the year in Saint John and about average for rainfall, so plan for around 15.3°C daytime highs and 4.9°C at night.
Not quite — May is the 8th coolest month in Saint John, averaging 10.1°C.
For May in Saint John, pack warm layers and a jacket for chilly mornings, with typical highs of 15.3°C and lows of 4.9°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 82% — quite humid.
Average wind speed in May is 0.5 m/s. The windiest May on record averaged 0.6 m/s (2002).
The wettest May on record was 1990 with 206 mm. On average, May sees 97 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 Saint John 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.
