March is one of the cooler months of the year in Merthyr Tydfil, with average highs near 9.4°C and lows around 3.5°C (mean 6.5°C). It is about average for rainfall, averaging 71 mm of rainfall and 89% relative humidity across the period.
March is one of the cooler months of the year in Merthyr Tydfil. Across 45 years of records, the warmest Marchs in Merthyr Tydfil were 2012 and 2017 — when the month averaged 8.1°C — while the coldest was 2013 at 3°C. Typical March days reach 9.4°C with nights near 3.5°C. The long-term trend is warming, about 0.2°C per decade.
March is about average for rainfall in Merthyr Tydfil, averaging 71 mm of rainfall. The wettest March on record was 2023 with 140 mm, while the driest was 2025 at 16 mm.
Relative humidity in Merthyr Tydfil during March averages 89%. The most humid March was 2024 at 92%, and the least humid were 1990, 1995 and 2008 at 87%.
March receives about 2.5 kWh/m²/day of solar energy in Merthyr Tydfil. The sunniest March was 2025 at 3.2 kWh/m²/day, and the cloudiest was 1996 at 1.8.
Average wind speed in Merthyr Tydfil during March is 4.1 m/s. The windiest March was 1994 at 5.4 m/s, while the calmest were 2012 and 2025 at 2.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 5.8°C | 6.9°C | 6.5°C | 6.2°C | 7.1°C | +1.3°C |
| Avg High | 8.6°C | 9.8°C | 9.4°C | 9.3°C | 10.2°C | +1.6°C |
| Avg Low | 2.9°C | 3.9°C | 3.5°C | 3.2°C | 4.0°C | +1.1°C |
| Avg Rain | 85 mm | 61 mm | 71 mm | 67 mm | 75 mm | -10 mm |
March temperatures in Merthyr Tydfil have risen by about 1.4°C between 1981–1985 and 2021–2025.
March has ranged from a record low of -5.7°C (2018) to a record high of 17.6°C (2021).
Rainfall in March is about average for rainfall, averaging 71 mm, with a wettest year of 140 mm.
A quieter season to visit Merthyr Tydfil
If your dates are flexible, the more temperate months of July and August tend to be the most comfortable for visiting Merthyr Tydfil. That said, March — with days averaging 9.4°C and nights around 3.5°C (mean 6.5°C) and moderate rainfall (71 mm) — can still be rewarding for travellers who don't mind the cooler conditions, and often means fewer crowds.
| Year | Avg High | Avg Temp | Avg Low | Hottest Day | Coldest Day | Rainfall | Humidity | Wind | Solar |
|---|---|---|---|---|---|---|---|---|---|
| 2025 | 10.9°C | 7.1°C | 3.4°C | 15.9°C | -1.4°C | 16 mm | 88% | 2.9 m/s | 3.2 |
| 2024 | 10.2°C | 7.6°C | 5.1°C | 13.9°C | 1.7°C | 115 mm | 92% | 4 m/s | 2.5 |
| 2023 🌧️ | 9.6°C | 7.0°C | 4.5°C | 13.5°C | -0.8°C | 140 mm | 91% | 4.3 m/s | 2.2 |
| 2022 | 11.2°C | 7.6°C | 3.9°C | 16.0°C | 0.6°C | 47 mm | 87% | 3.7 m/s | 3 |
| 2021 | 9.7°C | 6.8°C | 3.8°C | 17.6°C | -1.1°C | 56 mm | 89% | 4 m/s | 2.7 |
| 2020 | 9.3°C | 6.2°C | 3.1°C | 14.0°C | -1.0°C | 76 mm | 89% | 4.8 m/s | 3 |
| 2019 | 10.4°C | 7.7°C | 5.0°C | 13.0°C | 1.9°C | 105 mm | 89% | 4.6 m/s | 2.7 |
| 2018 | 7.3°C | 4.6°C | 1.9°C | 11.0°C | -5.7°C | 127 mm | 91% | 4.3 m/s | 2.2 |
| 2017 | 10.9°C | 8.1°C | 5.3°C | 15.2°C | 1.1°C | 83 mm | 89% | 4.4 m/s | 2.5 |
| 2016 | 8.7°C | 5.6°C | 2.5°C | 11.5°C | -1.1°C | 86 mm | 88% | 3.9 m/s | 2.8 |
| 2015 | 9.1°C | 6.0°C | 2.9°C | 12.1°C | 0.5°C | 53 mm | 89% | 4.3 m/s | 2.7 |
| 2014 | 10.1°C | 7.1°C | 4.2°C | 15.3°C | -0.1°C | 32 mm | 90% | 3.8 m/s | 2.8 |
| 2013 ❄️ | 5.8°C | 3.0°C | 0.3°C | 11.6°C | -2.8°C | 70 mm | 89% | 4 m/s | 2.2 |
| 2012 🔥 | 11.7°C | 8.1°C | 4.5°C | 17.3°C | 1.4°C | 25 mm | 87% | 2.9 m/s | 3.1 |
| 2011 | 10.4°C | 6.8°C | 3.2°C | 15.8°C | -2.0°C | 23 mm | 89% | 3 m/s | 3 |
| 2010 | 8.5°C | 5.4°C | 2.3°C | 11.3°C | -3.1°C | 66 mm | 90% | 3.6 m/s | 2.7 |
| 2009 | 9.7°C | 6.6°C | 3.5°C | 13.1°C | 0.1°C | 44 mm | 88% | 3.9 m/s | 3 |
| 2008 | 8.9°C | 6.2°C | 3.5°C | 11.9°C | -0.6°C | 111 mm | 87% | 5.1 m/s | 2.7 |
| 2007 | 10.1°C | 7.0°C | 3.8°C | 14.4°C | -1.2°C | 67 mm | 88% | 4.4 m/s | 3 |
| 2006 | 7.6°C | 5.1°C | 2.6°C | 13.4°C | -2.0°C | 86 mm | 88% | 4.8 m/s | 2.3 |
| 2005 | 10.0°C | 6.8°C | 3.7°C | 16.7°C | -2.5°C | 71 mm | 89% | 3.5 m/s | 2.3 |
| 2004 | 9.2°C | 6.2°C | 3.2°C | 14.7°C | -2.0°C | 63 mm | 89% | 3.9 m/s | 2.5 |
| 2003 | 11.0°C | 7.3°C | 3.6°C | 14.4°C | -0.4°C | 43 mm | 89% | 3.7 m/s | 3.1 |
| 2002 | 10.3°C | 7.4°C | 4.5°C | 13.8°C | -0.7°C | 58 mm | 90% | 4 m/s | 2.5 |
| 2001 | 7.6°C | 5.2°C | 2.9°C | 12.2°C | -2.2°C | 118 mm | 92% | 3.9 m/s | 2 |
| 2000 | 10.0°C | 6.8°C | 3.7°C | 13.8°C | -0.4°C | 45 mm | 89% | 3.8 m/s | 2.7 |
| 1999 | 9.8°C | 6.9°C | 4.0°C | 15.9°C | 0.8°C | 64 mm | 90% | 3.8 m/s | 2.5 |
| 1998 | 10.6°C | 7.9°C | 5.2°C | 15.3°C | 1.2°C | 102 mm | 90% | 4 m/s | 2.2 |
| 1997 | 11.1°C | 7.9°C | 4.8°C | 14.4°C | 2.2°C | 43 mm | 90% | 3.7 m/s | 2.7 |
| 1996 | 8.0°C | 4.8°C | 1.6°C | 14.5°C | -2.0°C | 73 mm | 88% | 3.6 m/s | 1.8 |
| 1995 | 8.2°C | 5.3°C | 2.3°C | 14.0°C | -1.7°C | 61 mm | 87% | 4.6 m/s | 2.6 |
| 1994 | 9.6°C | 7.0°C | 4.4°C | 13.8°C | 0.4°C | 91 mm | 90% | 5.4 m/s | 2.4 |
| 1993 | 9.5°C | 6.4°C | 3.3°C | 14.3°C | -0.8°C | 27 mm | 88% | 3.7 m/s | 2.4 |
| 1992 | 9.9°C | 7.1°C | 4.3°C | 12.5°C | 0.1°C | 54 mm | 88% | 5 m/s | 2.2 |
| 1991 | 10.8°C | 7.6°C | 4.5°C | 15.3°C | 0.0°C | 76 mm | 89% | 3.7 m/s | 2 |
| 1990 | 10.7°C | 7.8°C | 4.8°C | 16.0°C | -0.8°C | 20 mm | 87% | 4.4 m/s | 2.6 |
| 1989 | 10.2°C | 7.3°C | 4.4°C | 14.9°C | -0.8°C | 94 mm | 89% | 4.8 m/s | 2.1 |
| 1988 | 8.8°C | 6.4°C | 3.9°C | 11.6°C | -1.7°C | 95 mm | 90% | 4.7 m/s | 2.1 |
| 1987 | 7.3°C | 4.5°C | 1.6°C | 12.7°C | -2.7°C | 83 mm | 89% | 4.5 m/s | 2.3 |
| 1986 | 7.6°C | 4.6°C | 1.7°C | 10.0°C | -4.6°C | 80 mm | 90% | 4.4 m/s | 2.5 |
| 1985 | 7.5°C | 4.7°C | 1.8°C | 12.2°C | -3.4°C | 64 mm | 89% | 3.8 m/s | 2.2 |
| 1984 | 7.8°C | 4.6°C | 1.4°C | 11.7°C | -1.3°C | 39 mm | 88% | 3.5 m/s | 2.2 |
| 1983 | 8.8°C | 6.0°C | 3.3°C | 12.0°C | -1.9°C | 53 mm | 91% | 3.9 m/s | — |
| 1982 | 9.0°C | 5.9°C | 2.9°C | 13.5°C | 0.0°C | 119 mm | 88% | 4.5 m/s | — |
| 1981 | 10.1°C | 7.8°C | 5.4°C | 13.3°C | -1.5°C | 138 mm | 91% | 4.9 m/s | — |
Actual recorded March data for each year, 1981–2025 — sourced from NASA POWER.
The average high in March is around 9.4°C with lows near 3.5°C (mean 6.5°C), based on 45 years of NASA POWER data.
March averages 71 mm of rainfall in Merthyr Tydfil, about average for rainfall. The wettest on record was 140 mm in 2023.
The hottest March reached 17.6°C in 2021. The coldest dipped to -5.7°C in 2018.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average March temperatures have risen by about 1.4°C. Daytime highs moved from 8.6°C to 10.3°C and overnight lows from 3°C to 4.1°C over the same span.
March is one of the cooler months of the year in Merthyr Tydfil and about average for rainfall, so plan for around 9.4°C daytime highs and 3.5°C at night.
Not quite — March is the 4th coolest month in Merthyr Tydfil, averaging 6.5°C.
For March in Merthyr Tydfil, pack warm layers and a jacket for chilly mornings, with typical highs of 9.4°C and lows of 3.5°C. Bring an umbrella or light rain jacket too.
Relative humidity in March averages 89% — quite humid.
Average wind speed in March is 4.1 m/s. The windiest March on record averaged 5.4 m/s (1994).
The wettest March on record was 2023 with 140 mm. On average, March sees 71 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 Merthyr Tydfil behaves each March, 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 March specifically, along with year-by-year records and how the month has changed over the decades.
