December is one of the cooler months of the year in Mcallen, with average highs near 23.6°C and lows around 11.7°C (mean 17.7°C). It is one of the drier months, averaging 28 mm of rainfall and 71% relative humidity across the period.
December is one of the cooler months of the year in Mcallen. Across 45 years of records, the warmest December in Mcallen was 2021 — when the month averaged 21.6°C — while the coldest was 1989 at 11.1°C. Typical December days reach 23.6°C with nights near 11.7°C. The long-term trend is warming, about 0.4°C per decade.
December is one of the drier months in Mcallen, averaging 28 mm of rainfall. The wettest December on record was 2009 with 101 mm, while the driest were 2007 and 2010 at 1 mm.
Relative humidity in Mcallen during December averages 71%. The most humid December was 2014 at 81%, and the least humid was 1999 at 62%.
December receives about 2.9 kWh/m²/day of solar energy in Mcallen. The sunniest December was 2020 at 3.8 kWh/m²/day, and the cloudiest was 1986 at 2.
Average wind speed in Mcallen during December is 3.1 m/s. The windiest Decembers were 1984 and 2008 at 3.5 m/s, while the calmest was 2023 at 2.2 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 16.8°C | 18.0°C | 16.8°C | 17.9°C | 19.3°C | +2.5°C |
| Avg High | 22.8°C | 23.8°C | 22.9°C | 23.8°C | 25.4°C | +2.6°C |
| Avg Low | 10.8°C | 12.2°C | 10.8°C | 11.9°C | 13.3°C | +2.5°C |
| Avg Rain | 31 mm | 22 mm | 27 mm | 31 mm | 28 mm | -3 mm |
December temperatures in Mcallen have risen by about 2.3°C between 1981–1985 and 2021–2025.
December has ranged from a record low of -8.2°C (1989) to a record high of 33.4°C (2012).
Rainfall in December is one of the drier months, averaging 28 mm, with a wettest year of 101 mm.
A good time to visit Mcallen
December is a good time to visit Mcallen, with days averaging 23.6°C and nights around 11.7°C (mean 17.7°C, cooler than Mcallen's yearly average) and low rainfall. March and November are marginally more temperate, but December still suits most travellers.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 26.5°C | 20.1°C | 13.8°C | 31.6°C | 7.3°C | 25 mm | 72% | 2.5 m/s | — |
| 2024 | 26.2°C | 20.6°C | 15.0°C | 32.1°C | 5.4°C | 55 mm | 76% | 2.7 m/s | 2.9 |
| 2023 | 24.0°C | 18.5°C | 13.0°C | 30.6°C | 6.3°C | 15 mm | 76% | 2.2 m/s | 3 |
| 2022 | 24.0°C | 17.9°C | 11.9°C | 32.0°C | -3.4°C | 9 mm | 74% | 2.9 m/s | 3.1 |
| 2021 🔥 | 27.3°C | 21.6°C | 15.9°C | 32.1°C | 7.9°C | 36 mm | 80% | 3.2 m/s | 3.5 |
| 2020 | 24.1°C | 17.2°C | 10.4°C | 31.8°C | 2.4°C | 28 mm | 63% | 3.2 m/s | 3.8 |
| 2019 | 24.6°C | 18.1°C | 11.5°C | 32.1°C | 2.9°C | 25 mm | 69% | 2.8 m/s | 3.3 |
| 2018 | 23.4°C | 17.3°C | 11.1°C | 28.1°C | 5.5°C | 16 mm | 71% | 3.2 m/s | 3.2 |
| 2017 | 21.6°C | 16.0°C | 10.3°C | 31.2°C | 1.0°C | 27 mm | 73% | 2.9 m/s | 2.4 |
| 2016 | 25.4°C | 19.7°C | 14.0°C | 33.2°C | 1.2°C | 29 mm | 74% | 3.2 m/s | 2.2 |
| 2015 | 24.5°C | 18.6°C | 12.8°C | 31.2°C | 6.8°C | 6 mm | 74% | 3.2 m/s | 3.1 |
| 2014 | 23.6°C | 18.4°C | 13.2°C | 28.5°C | 5.0°C | 55 mm | 81% | 3 m/s | 2.4 |
| 2013 | 21.0°C | 15.4°C | 9.7°C | 31.5°C | 3.0°C | 89 mm | 76% | 2.9 m/s | 2.7 |
| 2012 | 26.6°C | 20.1°C | 13.5°C | 33.4°C | 5.2°C | 3 mm | 64% | 3.4 m/s | 3.2 |
| 2011 | 23.1°C | 17.5°C | 11.8°C | 29.6°C | 2.9°C | 60 mm | 71% | 3.4 m/s | 2.7 |
| 2010 | 24.5°C | 17.7°C | 10.8°C | 30.9°C | 1.5°C | 1 mm | 65% | 3.3 m/s | 3.7 |
| 2009 🌧️ | 19.5°C | 14.0°C | 8.4°C | 31.0°C | -1.5°C | 101 mm | 79% | 2.8 m/s | 2.6 |
| 2008 | 24.3°C | 17.9°C | 11.5°C | 32.6°C | 1.5°C | 5 mm | 69% | 3.5 m/s | 3 |
| 2007 | 25.6°C | 19.2°C | 12.8°C | 32.3°C | 3.8°C | 1 mm | 66% | 3.4 m/s | 3.5 |
| 2006 | 22.6°C | 16.8°C | 11.1°C | 29.0°C | 1.7°C | 65 mm | 75% | 3 m/s | 2.7 |
| 2005 | 23.8°C | 17.7°C | 11.7°C | 31.6°C | 2.3°C | 26 mm | 69% | 2.9 m/s | 2.8 |
| 2004 | 23.1°C | 16.8°C | 10.6°C | 31.4°C | -2.3°C | 19 mm | 67% | 3 m/s | 3.1 |
| 2003 | 22.4°C | 16.2°C | 10.1°C | 27.4°C | 0.9°C | 1 mm | 71% | 3.1 m/s | 3.7 |
| 2002 | 22.1°C | 16.4°C | 10.6°C | 29.2°C | 2.9°C | 5 mm | 78% | 3.2 m/s | 3.1 |
| 2001 | 23.9°C | 18.0°C | 12.0°C | 31.8°C | 3.1°C | 25 mm | 71% | 3.1 m/s | 3 |
| 2000 | 21.5°C | 15.3°C | 9.1°C | 30.1°C | 2.9°C | 20 mm | 72% | 3.2 m/s | 2.7 |
| 1999 | 23.9°C | 17.2°C | 10.6°C | 30.4°C | 3.8°C | 12 mm | 62% | 3.4 m/s | 3.5 |
| 1998 | 23.2°C | 17.4°C | 11.6°C | 32.0°C | 0.5°C | 9 mm | 73% | 3.3 m/s | 3.1 |
| 1997 | 22.7°C | 16.2°C | 9.7°C | 31.8°C | 1.6°C | 12 mm | 65% | 3 m/s | 3.3 |
| 1996 | 24.6°C | 18.3°C | 12.0°C | 30.7°C | -2.2°C | 9 mm | 70% | 2.9 m/s | 3.1 |
| 1995 | 22.8°C | 17.7°C | 12.5°C | 32.3°C | 2.4°C | 28 mm | 75% | 2.9 m/s | 2.8 |
| 1994 | 25.5°C | 20.1°C | 14.7°C | 32.9°C | 5.1°C | 33 mm | 74% | 3 m/s | 2.3 |
| 1993 | 23.9°C | 18.2°C | 12.5°C | 31.1°C | 3.7°C | 43 mm | 71% | 3.2 m/s | 2.6 |
| 1992 | 24.7°C | 19.0°C | 13.3°C | 29.8°C | 6.5°C | 17 mm | 78% | 2.9 m/s | 2.1 |
| 1991 | 22.9°C | 18.4°C | 13.8°C | 29.9°C | 4.9°C | 53 mm | 77% | 3.2 m/s | 2.1 |
| 1990 | 23.8°C | 17.5°C | 11.1°C | 32.4°C | -0.2°C | 9 mm | 65% | 3.3 m/s | 3.1 |
| 1989 ❄️ | 17.4°C | 11.1°C | 4.9°C | 29.0°C | -8.2°C | 54 mm | 65% | 3.2 m/s | 3 |
| 1988 | 24.4°C | 18.4°C | 12.5°C | 30.3°C | 4.5°C | 2 mm | 68% | 3 m/s | 3.2 |
| 1987 | 24.5°C | 18.6°C | 12.6°C | 32.5°C | 5.3°C | 14 mm | 71% | 2.8 m/s | 2.6 |
| 1986 | 21.2°C | 16.0°C | 10.7°C | 29.5°C | 2.4°C | 85 mm | 76% | 2.9 m/s | 2 |
| 1985 | 22.1°C | 15.8°C | 9.5°C | 29.6°C | 0.1°C | 21 mm | 71% | 2.8 m/s | 2.8 |
| 1984 | 26.6°C | 21.3°C | 15.9°C | 31.5°C | 4.2°C | 33 mm | 77% | 3.5 m/s | 2.8 |
| 1983 | 20.7°C | 14.0°C | 7.3°C | 32.3°C | -7.4°C | 15 mm | 63% | 3.2 m/s | — |
| 1982 | 23.2°C | 17.2°C | 11.3°C | 32.8°C | 4.6°C | 55 mm | 68% | 3.2 m/s | — |
| 1981 | 24.8°C | 18.5°C | 12.2°C | 31.6°C | 4.6°C | 5 mm | 68% | 2.8 m/s | — |
Actual recorded December data for each year, 1981–2025 — sourced from NASA POWER.
The average high in December is around 23.6°C with lows near 11.7°C (mean 17.7°C), based on 45 years of NASA POWER data.
December averages 28 mm of rainfall in Mcallen, one of the drier months. The wettest on record was 101 mm in 2009.
The hottest December reached 33.4°C in 2012. The coldest dipped to -8.2°C in 1989.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average December temperatures have risen by about 2.3°C. Daytime highs moved from 23.5°C to 25.6°C and overnight lows from 11.2°C to 13.9°C over the same span.
December is one of the cooler months of the year in Mcallen and one of the drier months, so plan for around 23.6°C daytime highs and 11.7°C at night.
Not quite — December is the 2nd coolest month in Mcallen, averaging 17.7°C.
For December in Mcallen, pack light layers you can adjust through the day, with typical highs of 23.6°C and lows of 11.7°C.
Relative humidity in December averages 71% — moderately humid.
Average wind speed in December is 3.1 m/s. The windiest December on record averaged 3.5 m/s (1984).
The wettest December on record was 2009 with 101 mm. On average, December sees 28 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 December, 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 December specifically, along with year-by-year records and how the month has changed over the decades.
