May is one of the warmer months of the year in Flagstaff, with average highs near 23.1°C and lows around 6.4°C (mean 14.8°C). It is one of the drier months, averaging 14 mm of rainfall and 38% relative humidity across the period.
May is one of the warmer months of the year in Flagstaff. Across 45 years of records, the warmest May in Flagstaff was 1984 — when the month averaged 17.4°C — while the coldest was 1995 at 11.2°C. Typical May days reach 23.1°C with nights near 6.4°C. The long-term trend is warming, about 0.2°C per decade.
May is one of the drier months in Flagstaff, averaging 14 mm of rainfall. The wettest May on record was 1992 with 92 mm, while the driest were 2012 and 2022 at 0 mm.
Relative humidity in Flagstaff during May averages 38%. The most humid May was 1992 at 63%, and the least humid was 2002 at 22%.
May receives about 7.8 kWh/m²/day of solar energy in Flagstaff. The sunniest May was 2002 at 8.6 kWh/m²/day, and the cloudiest was 1992 at 6.4.
Average wind speed in Flagstaff during May is 2.8 m/s. The windiest May was 1991 at 3.6 m/s, while the calmest were 1992 and 1997 at 2.1 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 14.4°C | 13.9°C | 16.1°C | 13.9°C | 15.9°C | +1.5°C |
| Avg High | 22.6°C | 22.0°C | 24.7°C | 22.2°C | 24.5°C | +1.9°C |
| Avg Low | 6.1°C | 5.9°C | 7.5°C | 5.5°C | 7.3°C | +1.2°C |
| Avg Rain | 14 mm | 20 mm | 13 mm | 15 mm | 7 mm | -6 mm |
May temperatures in Flagstaff have risen by about 1.1°C between 1981–1985 and 2021–2025.
May has ranged from a record low of -5.6°C (1988) to a record high of 35°C (2002).
Rainfall in May is one of the drier months, averaging 14 mm, with a wettest year of 92 mm.
A good time to visit Flagstaff
May is a good time to visit Flagstaff, with days averaging 23.1°C and nights around 6.4°C (mean 14.8°C, warmer than Flagstaff's yearly average) and low rainfall. June 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 | 23.9°C | 15.7°C | 7.5°C | 32.4°C | 2.7°C | 12 mm | 35% | 2.5 m/s | 7.6 |
| 2024 | 23.8°C | 15.1°C | 6.5°C | 31.4°C | -1.7°C | 2 mm | 35% | 2.6 m/s | 8 |
| 2023 | 22.7°C | 14.8°C | 6.9°C | 26.7°C | 0.5°C | 19 mm | 46% | 2.4 m/s | 7.7 |
| 2022 | 25.4°C | 16.5°C | 7.6°C | 32.2°C | -1.2°C | 0 mm | 25% | 3.4 m/s | 8.4 |
| 2021 | 25.2°C | 16.1°C | 7.1°C | 29.9°C | 0.3°C | 5 mm | 26% | 2.8 m/s | 8.2 |
| 2020 | 26.0°C | 17.2°C | 8.3°C | 33.1°C | 1.8°C | 5 mm | 34% | 2.8 m/s | 8.3 |
| 2019 | 18.8°C | 11.4°C | 4.1°C | 26.9°C | 0.0°C | 43 mm | 52% | 2.7 m/s | 7 |
| 2018 | 24.8°C | 16.2°C | 7.5°C | 31.1°C | -1.3°C | 10 mm | 30% | 2.9 m/s | 8.1 |
| 2017 | 22.5°C | 14.2°C | 5.8°C | 29.3°C | -0.1°C | 16 mm | 44% | 2.7 m/s | 7.9 |
| 2016 | 21.2°C | 13.4°C | 5.5°C | 28.7°C | 0.3°C | 25 mm | 44% | 2.6 m/s | 7.5 |
| 2015 | 19.8°C | 12.3°C | 4.7°C | 30.8°C | -0.7°C | 37 mm | 51% | 2.6 m/s | 6.8 |
| 2014 | 22.8°C | 14.3°C | 5.8°C | 31.4°C | -1.8°C | 2 mm | 32% | 3 m/s | 7.7 |
| 2013 | 23.8°C | 15.0°C | 6.2°C | 29.5°C | -0.3°C | 2 mm | 31% | 3 m/s | 7.9 |
| 2012 | 25.6°C | 16.5°C | 7.5°C | 31.3°C | 1.0°C | 0 mm | 26% | 3 m/s | 8.5 |
| 2011 | 21.0°C | 12.5°C | 4.0°C | 28.2°C | -3.6°C | 18 mm | 35% | 3.5 m/s | 8.1 |
| 2010 | 21.4°C | 12.7°C | 3.9°C | 27.2°C | -3.0°C | 2 mm | 36% | 3.3 m/s | 8.3 |
| 2009 | 25.2°C | 17.2°C | 9.1°C | 30.5°C | 6.5°C | 52 mm | 41% | 2.2 m/s | 7.1 |
| 2008 | 20.7°C | 12.4°C | 4.1°C | 31.9°C | -3.9°C | 22 mm | 41% | 2.9 m/s | 7.8 |
| 2007 | 24.0°C | 15.8°C | 7.6°C | 30.2°C | -1.1°C | 9 mm | 36% | 2.5 m/s | 7.7 |
| 2006 | 26.1°C | 17.1°C | 8.1°C | 30.5°C | 3.2°C | 2 mm | 29% | 2.5 m/s | 8.1 |
| 2005 | 23.6°C | 15.5°C | 7.4°C | 31.8°C | -1.2°C | 8 mm | 46% | 2.5 m/s | 8 |
| 2004 | 24.9°C | 16.3°C | 7.6°C | 30.5°C | 1.6°C | 0 mm | 27% | 3.1 m/s | 8.4 |
| 2003 | 25.0°C | 16.4°C | 7.9°C | 33.3°C | -2.0°C | 7 mm | 33% | 2.8 m/s | 7.6 |
| 2002 | 25.0°C | 15.7°C | 6.4°C | 35.0°C | 0.3°C | 1 mm | 22% | 2.9 m/s | 8.6 |
| 2001 | 26.3°C | 17.3°C | 8.3°C | 31.8°C | -1.2°C | 23 mm | 33% | 2.4 m/s | 7.8 |
| 2000 | 26.3°C | 17.2°C | 8.1°C | 33.8°C | -0.5°C | 2 mm | 27% | 3.1 m/s | 8.1 |
| 1999 | 22.5°C | 14.0°C | 5.6°C | 27.7°C | -3.1°C | 5 mm | 35% | 2.9 m/s | 8.1 |
| 1998 | 20.6°C | 12.3°C | 4.0°C | 27.3°C | -1.2°C | 16 mm | 47% | 3.3 m/s | 8.1 |
| 1997 | 25.6°C | 17.2°C | 8.8°C | 33.3°C | -1.5°C | 16 mm | 39% | 2.1 m/s | 7.3 |
| 1996 | 25.2°C | 16.3°C | 7.4°C | 32.3°C | 0.8°C | 1 mm | 27% | 3.3 m/s | 8.2 |
| 1995 ❄️ | 18.8°C | 11.2°C | 3.7°C | 25.8°C | -2.3°C | 20 mm | 53% | 3 m/s | 7.2 |
| 1994 | 21.8°C | 13.7°C | 5.5°C | 29.9°C | 1.4°C | 24 mm | 45% | 2.6 m/s | 7.2 |
| 1993 | 22.0°C | 14.2°C | 6.3°C | 27.5°C | -2.1°C | 14 mm | 53% | 2.4 m/s | 7.5 |
| 1992 🌧️ | 20.4°C | 14.2°C | 7.9°C | 27.0°C | 4.7°C | 92 mm | 63% | 2.1 m/s | 6.4 |
| 1991 | 20.7°C | 12.3°C | 4.0°C | 26.2°C | -2.1°C | 3 mm | 38% | 3.6 m/s | 7.8 |
| 1990 | 22.1°C | 13.8°C | 5.4°C | 28.7°C | -0.4°C | 13 mm | 34% | 3.3 m/s | 8 |
| 1989 | 24.3°C | 15.5°C | 6.8°C | 30.9°C | -0.5°C | 12 mm | 33% | 3.2 m/s | 8 |
| 1988 | 21.9°C | 13.5°C | 5.2°C | 28.6°C | -5.6°C | 3 mm | 40% | 2.7 m/s | 7.5 |
| 1987 | 20.8°C | 13.3°C | 5.7°C | 25.7°C | 0.1°C | 23 mm | 51% | 2.2 m/s | 7.3 |
| 1986 | 23.0°C | 14.5°C | 6.0°C | 30.0°C | -2.3°C | 10 mm | 37% | 2.8 m/s | 7.6 |
| 1985 | 22.4°C | 14.6°C | 6.8°C | 27.3°C | -0.3°C | 6 mm | 44% | 2.5 m/s | 7.3 |
| 1984 🔥 | 26.5°C | 17.4°C | 8.3°C | 31.6°C | -0.2°C | 7 mm | 35% | 2.7 m/s | 7.6 |
| 1983 | 21.2°C | 12.9°C | 4.6°C | 29.6°C | -2.7°C | 3 mm | 45% | 2.7 m/s | — |
| 1982 | 21.4°C | 13.4°C | 5.4°C | 27.7°C | -0.8°C | 34 mm | 44% | 2.7 m/s | — |
| 1981 | 22.0°C | 14.1°C | 6.1°C | 26.8°C | -0.9°C | 23 mm | 36% | 2.9 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 23.1°C with lows near 6.4°C (mean 14.8°C), based on 45 years of NASA POWER data.
May averages 14 mm of rainfall in Flagstaff, one of the drier months. The wettest on record was 92 mm in 1992.
The hottest May reached 35°C in 2002. The coldest dipped to -5.6°C in 1988.
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 22.7°C to 24.2°C and overnight lows from 6.2°C to 7.1°C over the same span.
May is one of the warmer months of the year in Flagstaff and one of the drier months, so plan for around 23.1°C daytime highs and 6.4°C at night.
Not quite — May is the 8th coolest month in Flagstaff, averaging 14.8°C.
For May in Flagstaff, pack warm layers and a jacket for chilly mornings, with typical highs of 23.1°C and lows of 6.4°C.
Relative humidity in May averages 38% — relatively dry.
Average wind speed in May is 2.8 m/s. The windiest May on record averaged 3.6 m/s (1991).
The wettest May on record was 1992 with 92 mm. On average, May sees 14 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 Flagstaff 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.
