May is one of the warmer months of the year in Mcallen, with average highs near 35°C and lows around 22.6°C (mean 28.8°C). It is a relatively wet time of year, averaging 68 mm of rainfall and 67% relative humidity across the period.
May is one of the warmer months of the year in Mcallen. Across 45 years of records, the warmest May in Mcallen was 2024 — when the month averaged 32.5°C — while the coldest was 1992 at 26.1°C. Typical May days reach 35°C with nights near 22.6°C. The long-term trend is warming, about 0.3°C per decade.
May is a relatively wet time of year in Mcallen, averaging 68 mm of rainfall. The wettest May on record was 2015 with 174 mm, while the driest was 1998 at 0 mm.
Relative humidity in Mcallen during May averages 67%. The most humid May was 2015 at 76%, and the least humid was 1998 at 59%.
May receives about 6.1 kWh/m²/day of solar energy in Mcallen. The sunniest Mays were 1998 and 2018 at 6.9 kWh/m²/day, and the cloudiest was 2015 at 5.2.
Average wind speed in Mcallen during May is 3.9 m/s. The windiest May was 1996 at 5 m/s, while the calmest was 2023 at 2.6 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 28.0°C | 28.8°C | 29.2°C | 28.7°C | 29.5°C | +1.5°C |
| Avg High | 34.2°C | 35.3°C | 35.6°C | 34.7°C | 35.4°C | +1.2°C |
| Avg Low | 21.9°C | 22.4°C | 22.8°C | 22.6°C | 23.7°C | +1.8°C |
| Avg Rain | 90 mm | 68 mm | 39 mm | 60 mm | 98 mm | +7 mm |
May temperatures in Mcallen have risen by about 1.8°C between 1981–1985 and 2021–2025.
May has ranged from a record low of 11.2°C (2013) to a record high of 45.8°C (1998).
Rainfall in May is a relatively wet time of year, averaging 68 mm, with a wettest year of 174 mm.
Daytime highs and overnight lows have shifted differently — highs rose about 0.2°C per decade while lows rose 0.4°C per decade, narrowing the gap between day and night.
A good time to visit Mcallen
May is a good time to visit Mcallen, with days averaging 35°C and nights around 22.6°C (mean 28.8°C, warmer than Mcallen's yearly average) and moderate rainfall. March and November 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 | 36.0°C | 29.9°C | 23.8°C | 41.1°C | 17.9°C | 92 mm | 69% | 3.6 m/s | 5.9 |
| 2024 🔥 | 39.1°C | 32.5°C | 25.9°C | 44.8°C | 23.4°C | 14 mm | 66% | 3.7 m/s | 5.6 |
| 2023 | 33.0°C | 27.8°C | 22.6°C | 36.3°C | 17.3°C | 100 mm | 74% | 2.6 m/s | 5.6 |
| 2022 | 35.8°C | 29.7°C | 23.6°C | 41.9°C | 21.0°C | 98 mm | 70% | 4.4 m/s | 6.6 |
| 2021 | 33.6°C | 28.1°C | 22.7°C | 42.3°C | 18.0°C | 171 mm | 73% | 3.8 m/s | 6 |
| 2020 | 34.8°C | 29.1°C | 23.4°C | 39.0°C | 18.6°C | 111 mm | 68% | 3.9 m/s | 6 |
| 2019 | 35.8°C | 29.9°C | 24.1°C | 40.5°C | 19.5°C | 30 mm | 69% | 4.2 m/s | 5.6 |
| 2018 | 35.9°C | 29.2°C | 22.6°C | 39.5°C | 18.0°C | 25 mm | 63% | 3.9 m/s | 6.9 |
| 2017 | 35.8°C | 29.3°C | 22.8°C | 40.8°C | 16.2°C | 60 mm | 62% | 4 m/s | 6 |
| 2016 | 34.0°C | 28.5°C | 23.1°C | 38.5°C | 17.4°C | 85 mm | 69% | 3.6 m/s | 5.3 |
| 2015 🌧️ | 32.4°C | 27.9°C | 23.3°C | 37.0°C | 14.6°C | 174 mm | 76% | 4.2 m/s | 5.2 |
| 2014 | 32.8°C | 26.7°C | 20.5°C | 37.9°C | 13.4°C | 63 mm | 65% | 4.2 m/s | 6.3 |
| 2013 | 34.1°C | 27.9°C | 21.6°C | 38.9°C | 11.2°C | 48 mm | 65% | 4.4 m/s | 5.7 |
| 2012 | 35.4°C | 29.0°C | 22.5°C | 39.8°C | 18.6°C | 47 mm | 65% | 3.9 m/s | 6.7 |
| 2011 | 36.8°C | 29.9°C | 23.0°C | 43.6°C | 16.2°C | 3 mm | 60% | 4.8 m/s | 6.1 |
| 2010 | 34.5°C | 28.4°C | 22.3°C | 36.4°C | 15.7°C | 63 mm | 67% | 4.2 m/s | 6.4 |
| 2009 | 35.5°C | 29.1°C | 22.7°C | 41.1°C | 16.3°C | 72 mm | 64% | 3.9 m/s | 6.3 |
| 2008 | 36.7°C | 30.0°C | 23.3°C | 42.4°C | 18.0°C | 25 mm | 63% | 3.9 m/s | 6.3 |
| 2007 | 33.3°C | 27.8°C | 22.3°C | 38.4°C | 18.5°C | 68 mm | 69% | 3.7 m/s | 5.6 |
| 2006 | 36.0°C | 29.5°C | 23.0°C | 40.8°C | 18.1°C | 42 mm | 62% | 4.1 m/s | 6.5 |
| 2005 | 34.9°C | 28.5°C | 22.1°C | 40.6°C | 15.6°C | 30 mm | 64% | 3.9 m/s | 5.8 |
| 2004 | 33.2°C | 27.4°C | 21.6°C | 42.8°C | 13.0°C | 44 mm | 70% | 4.4 m/s | 6.1 |
| 2003 | 37.7°C | 30.8°C | 24.0°C | 44.1°C | 21.8°C | 25 mm | 64% | 4.1 m/s | 6.1 |
| 2002 | 36.3°C | 29.7°C | 23.0°C | 43.7°C | 17.0°C | 35 mm | 61% | 4.7 m/s | 6.8 |
| 2001 | 35.8°C | 28.9°C | 22.1°C | 40.9°C | 19.0°C | 16 mm | 63% | 4.1 m/s | 6.7 |
| 2000 | 36.7°C | 30.2°C | 23.7°C | 39.9°C | 21.7°C | 29 mm | 66% | 4.6 m/s | 6.4 |
| 1999 | 37.2°C | 30.3°C | 23.3°C | 43.0°C | 20.1°C | 20 mm | 62% | 4.2 m/s | 6.7 |
| 1998 | 39.7°C | 31.1°C | 22.6°C | 45.8°C | 18.5°C | 0 mm | 59% | 4.3 m/s | 6.9 |
| 1997 | 31.7°C | 26.2°C | 20.8°C | 37.0°C | 16.0°C | 99 mm | 76% | 2.9 m/s | 6 |
| 1996 | 36.1°C | 29.6°C | 23.2°C | 41.3°C | 16.4°C | 18 mm | 65% | 5 m/s | 6.7 |
| 1995 | 36.9°C | 30.3°C | 23.6°C | 44.7°C | 19.6°C | 90 mm | 64% | 4.3 m/s | 6 |
| 1994 | 35.6°C | 29.1°C | 22.6°C | 39.6°C | 17.6°C | 30 mm | 65% | 3.5 m/s | 6.2 |
| 1993 | 33.1°C | 26.9°C | 20.7°C | 37.5°C | 15.7°C | 125 mm | 69% | 3.3 m/s | 5.8 |
| 1992 ❄️ | 31.3°C | 26.1°C | 20.8°C | 36.9°C | 14.3°C | 155 mm | 74% | 3.2 m/s | 5.5 |
| 1991 | 35.5°C | 29.4°C | 23.3°C | 38.7°C | 19.2°C | 96 mm | 68% | 3.5 m/s | 5.9 |
| 1990 | 35.5°C | 29.1°C | 22.8°C | 40.4°C | 15.1°C | 49 mm | 67% | 4.1 m/s | 5.9 |
| 1989 | 37.2°C | 30.2°C | 23.2°C | 40.6°C | 18.2°C | 5 mm | 63% | 4.5 m/s | 6.7 |
| 1988 | 34.0°C | 27.6°C | 21.2°C | 39.5°C | 18.2°C | 39 mm | 64% | 3.5 m/s | 5.8 |
| 1987 | 33.6°C | 27.7°C | 21.9°C | 38.5°C | 17.9°C | 113 mm | 71% | 3.6 m/s | 5.8 |
| 1986 | 33.8°C | 27.9°C | 22.0°C | 37.5°C | 16.8°C | 96 mm | 68% | 3.5 m/s | 5.5 |
| 1985 | 33.7°C | 27.7°C | 21.7°C | 38.3°C | 17.6°C | 134 mm | 71% | 3.2 m/s | 6.3 |
| 1984 | 34.4°C | 27.9°C | 21.3°C | 42.8°C | 15.2°C | 70 mm | 65% | 3.6 m/s | 6 |
| 1983 | 35.3°C | 28.7°C | 22.1°C | 43.5°C | 16.3°C | 69 mm | 66% | 4.1 m/s | — |
| 1982 | 32.1°C | 27.0°C | 22.0°C | 37.1°C | 16.0°C | 150 mm | 75% | 3.8 m/s | — |
| 1981 | 33.3°C | 27.6°C | 21.9°C | 40.4°C | 16.7°C | 139 mm | 72% | 3.4 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 35°C with lows near 22.6°C (mean 28.8°C), based on 45 years of NASA POWER data.
May averages 68 mm of rainfall in Mcallen, a relatively wet time of year. The wettest on record was 174 mm in 2015.
The hottest May reached 45.8°C in 1998. The coldest dipped to 11.2°C in 2013.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 1.8°C. Daytime highs moved from 33.8°C to 35.5°C and overnight lows from 21.8°C to 23.7°C over the same span.
May is one of the warmer months of the year in Mcallen and a relatively wet time of year, so plan for around 35°C daytime highs and 22.6°C at night.
Not quite — May is the 9th coolest month in Mcallen, averaging 28.8°C.
For May in Mcallen, pack light, breathable clothing and sun protection, with typical highs of 35°C and lows of 22.6°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 67% — moderately humid.
Average wind speed in May is 3.9 m/s. The windiest May on record averaged 5 m/s (1996).
The wettest May on record was 2015 with 174 mm. On average, May sees 68 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 Mcallen 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.
