May is one of the cooler months of the year in Whanganui, with average highs near 15.3°C and lows around 10.4°C (mean 12.9°C). It is about average for rainfall, averaging 92 mm of rainfall and 84% relative humidity across the period.
May is one of the cooler months of the year in Whanganui. Across 45 years of records, the warmest May in Whanganui was 2016 — when the month averaged 14.8°C — while the coldest was 1992 at 10.1°C. Typical May days reach 15.3°C with nights near 10.4°C. The long-term trend is warming, about 0.2°C per decade.
May is about average for rainfall in Whanganui, averaging 92 mm of rainfall. The wettest May on record was 1989 with 168 mm, while the driest was 2007 at 23 mm.
Relative humidity in Whanganui during May averages 84%. The most humid May was 1997 at 87%, and the least humid was 2002 at 80%.
May receives about 2.1 kWh/m²/day of solar energy in Whanganui. The sunniest Mays were 2008 and 2020 at 2.4 kWh/m²/day, and the cloudiest were 2011, 2016 and 2023, among others at 1.9.
Average wind speed in Whanganui during May is 4.6 m/s. The windiest May was 1983 at 6.1 m/s, while the calmest was 1997 at 3.7 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 12.5°C | 12.5°C | 13.0°C | 13.2°C | 13.3°C | +0.8°C |
| Avg High | 15.0°C | 14.8°C | 15.4°C | 15.6°C | 15.8°C | +0.8°C |
| Avg Low | 10.0°C | 10.2°C | 10.5°C | 10.9°C | 10.7°C | +0.7°C |
| Avg Rain | 92 mm | 96 mm | 69 mm | 102 mm | 105 mm | +13 mm |
May temperatures in Whanganui have risen by about 1.1°C between 1981–1985 and 2021–2025.
May has ranged from a record low of 4.1°C (1992) to a record high of 22.2°C (1989).
Rainfall in May is about average for rainfall, averaging 92 mm, with a wettest year of 168 mm.
A good time to visit Whanganui
May is a good time to visit Whanganui, with days averaging 15.3°C and nights around 10.4°C (mean 12.9°C, close to Whanganui's yearly average) and higher rainfall. February and January 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 | 15.9°C | 13.3°C | 10.7°C | 19.4°C | 6.3°C | 96 mm | 84% | 4.6 m/s | 2.2 |
| 2024 | 14.3°C | 11.8°C | 9.3°C | 17.9°C | 5.6°C | 88 mm | 83% | 4 m/s | 2.3 |
| 2023 | 16.7°C | 14.4°C | 12.1°C | 20.6°C | 8.1°C | 150 mm | 87% | 4.1 m/s | 1.9 |
| 2022 | 16.6°C | 14.1°C | 11.6°C | 19.2°C | 6.4°C | 146 mm | 85% | 4.5 m/s | 2.2 |
| 2021 | 15.7°C | 13.2°C | 10.8°C | 19.7°C | 5.0°C | 65 mm | 83% | 5 m/s | 2.2 |
| 2020 | 15.7°C | 12.7°C | 9.6°C | 18.6°C | 6.1°C | 83 mm | 82% | 3.9 m/s | 2.4 |
| 2019 | 16.6°C | 14.1°C | 11.6°C | 19.1°C | 8.2°C | 74 mm | 83% | 4.9 m/s | 2.2 |
| 2018 | 15.2°C | 13.0°C | 10.9°C | 18.6°C | 7.0°C | 126 mm | 85% | 5 m/s | 2.1 |
| 2017 | 14.9°C | 12.6°C | 10.3°C | 18.9°C | 5.7°C | 120 mm | 84% | 4.3 m/s | 2.1 |
| 2016 🔥 | 17.0°C | 14.8°C | 12.6°C | 20.3°C | 6.3°C | 152 mm | 83% | 5.8 m/s | 1.9 |
| 2015 | 15.0°C | 12.8°C | 10.6°C | 19.0°C | 5.4°C | 131 mm | 83% | 4.9 m/s | 2.1 |
| 2014 | 15.5°C | 13.1°C | 10.8°C | 19.5°C | 5.9°C | 84 mm | 84% | 4.8 m/s | 2.2 |
| 2013 | 15.6°C | 13.0°C | 10.5°C | 19.1°C | 6.7°C | 70 mm | 83% | 4.2 m/s | 2.1 |
| 2012 | 14.4°C | 11.9°C | 9.3°C | 18.4°C | 5.2°C | 66 mm | 83% | 4.1 m/s | 2.2 |
| 2011 | 16.4°C | 14.1°C | 11.8°C | 19.6°C | 8.4°C | 96 mm | 86% | 5 m/s | 1.9 |
| 2010 | 15.6°C | 12.8°C | 10.1°C | 19.7°C | 6.8°C | 104 mm | 82% | 3.8 m/s | 2.2 |
| 2009 | 13.1°C | 11.0°C | 8.9°C | 17.5°C | 4.8°C | 108 mm | 84% | 5.4 m/s | 1.9 |
| 2008 | 14.1°C | 11.4°C | 8.8°C | 16.7°C | 6.1°C | 55 mm | 85% | 3.8 m/s | 2.4 |
| 2007 | 16.7°C | 14.0°C | 11.3°C | 18.9°C | 7.4°C | 23 mm | 85% | 4.7 m/s | 2.2 |
| 2006 | 15.2°C | 12.7°C | 10.3°C | 18.2°C | 6.2°C | 79 mm | 85% | 3.9 m/s | 2 |
| 2005 | 15.9°C | 13.5°C | 11.2°C | 19.3°C | 7.0°C | 86 mm | 86% | 4.6 m/s | 2 |
| 2004 | 15.4°C | 12.9°C | 10.5°C | 18.6°C | 7.6°C | 56 mm | 87% | 4.6 m/s | 2.2 |
| 2003 | 16.1°C | 13.5°C | 10.8°C | 19.6°C | 6.6°C | 79 mm | 82% | 4.5 m/s | 2.1 |
| 2002 | 15.8°C | 13.4°C | 11.0°C | 18.8°C | 6.6°C | 57 mm | 80% | 5.9 m/s | 2 |
| 2001 | 16.0°C | 13.8°C | 11.5°C | 20.9°C | 5.1°C | 84 mm | 82% | 4.9 m/s | 1.9 |
| 2000 | 16.1°C | 13.4°C | 10.7°C | 19.9°C | 6.8°C | 58 mm | 83% | 4.3 m/s | 2.1 |
| 1999 | 16.5°C | 14.0°C | 11.5°C | 20.2°C | 7.9°C | 73 mm | 84% | 4.7 m/s | 2 |
| 1998 | 15.3°C | 12.8°C | 10.2°C | 18.1°C | 6.4°C | 72 mm | 82% | 4.5 m/s | 2 |
| 1997 | 15.8°C | 13.3°C | 10.8°C | 17.7°C | 8.7°C | 40 mm | 87% | 3.7 m/s | 2.1 |
| 1996 | 14.3°C | 12.1°C | 9.8°C | 17.5°C | 5.2°C | 145 mm | 84% | 4.4 m/s | 2.1 |
| 1995 | 15.0°C | 12.6°C | 10.2°C | 20.0°C | 5.5°C | 110 mm | 85% | 4.2 m/s | 2.2 |
| 1994 | 15.0°C | 13.0°C | 11.0°C | 18.4°C | 7.6°C | 144 mm | 83% | 5.6 m/s | 2 |
| 1993 | 14.6°C | 12.5°C | 10.3°C | 17.8°C | 7.3°C | 117 mm | 86% | 4.7 m/s | 1.9 |
| 1992 ❄️ | 12.4°C | 10.1°C | 7.8°C | 17.4°C | 4.1°C | 81 mm | 85% | 4.6 m/s | 2.1 |
| 1991 | 14.2°C | 11.9°C | 9.7°C | 16.4°C | 6.9°C | 57 mm | 85% | 4.1 m/s | 2.1 |
| 1990 | 14.9°C | 13.0°C | 11.0°C | 17.1°C | 8.9°C | 122 mm | 83% | 5.4 m/s | 2 |
| 1989 🌧️ | 15.3°C | 13.0°C | 10.7°C | 22.2°C | 6.6°C | 168 mm | 85% | 3.9 m/s | 2 |
| 1988 | 15.1°C | 12.7°C | 10.3°C | 19.7°C | 6.3°C | 89 mm | 82% | 4.8 m/s | 2 |
| 1987 | 14.8°C | 12.4°C | 10.0°C | 17.0°C | 7.4°C | 83 mm | 86% | 4.1 m/s | 2 |
| 1986 | 15.6°C | 12.8°C | 10.1°C | 18.6°C | 5.1°C | 87 mm | 82% | 4.7 m/s | 2.3 |
| 1985 | 14.9°C | 12.1°C | 9.3°C | 18.5°C | 6.0°C | 38 mm | 84% | 4.2 m/s | 2.3 |
| 1984 | 14.5°C | 12.0°C | 9.6°C | 18.0°C | 4.9°C | 79 mm | 82% | 4.8 m/s | 2.2 |
| 1983 | 13.9°C | 11.9°C | 9.8°C | 20.2°C | 6.4°C | 103 mm | 84% | 6.1 m/s | — |
| 1982 | 15.1°C | 12.6°C | 10.0°C | 18.1°C | 6.7°C | 102 mm | 81% | 5.3 m/s | — |
| 1981 | 15.5°C | 12.7°C | 9.9°C | 21.0°C | 7.0°C | 75 mm | 83% | 4.1 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 10.4°C (mean 12.9°C), based on 45 years of NASA POWER data.
May averages 92 mm of rainfall in Whanganui, about average for rainfall. The wettest on record was 168 mm in 1989.
The hottest May reached 22.2°C in 1989. The coldest dipped to 4.1°C in 1992.
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 15.8°C and overnight lows from 9.7°C to 10.9°C over the same span.
May is one of the cooler months of the year in Whanganui and about average for rainfall, so plan for around 15.3°C daytime highs and 10.4°C at night.
Not quite — May is the 6th coolest month in Whanganui, averaging 12.9°C.
For May in Whanganui, pack light layers you can adjust through the day, with typical highs of 15.3°C and lows of 10.4°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 84% — quite humid.
Average wind speed in May is 4.6 m/s. The windiest May on record averaged 6.1 m/s (1983).
The wettest May on record was 1989 with 168 mm. On average, May sees 92 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 Whanganui 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.
