May is close to Llanelli's year-round average, with average highs near 13.6°C and lows around 9.5°C (mean 11.6°C). It is one of the drier months, averaging 68 mm of rainfall and 84% relative humidity across the period.
May is close to Llanelli's year-round average. Across 45 years of records, the warmest May in Llanelli was 2025 — when the month averaged 13.5°C — while the coldest was 1996 at 9.5°C. Typical May days reach 13.6°C with nights near 9.5°C. The long-term trend is warming, about 0.3°C per decade.
May is one of the drier months in Llanelli, averaging 68 mm of rainfall. The wettest May on record was 2021 with 180 mm, while the driest was 1991 at 11 mm.
Relative humidity in Llanelli during May averages 84%. The most humid May was 1981 at 87%, and the least humid was 2020 at 80%.
May receives about 5.5 kWh/m²/day of solar energy in Llanelli. The sunniest May was 2020 at 6.5 kWh/m²/day, and the cloudiest was 1999 at 4.7.
Average wind speed in Llanelli during May is 4.3 m/s. The windiest May was 2011 at 6.1 m/s, while the calmest was 2018 at 2.9 m/s.
Ranked against the other 11 months using 1981–2025 averages.
| Metric | 1980s | 1990s | 2000s | 2010s | 2020s | Change |
|---|---|---|---|---|---|---|
| Avg Temp | 10.9°C | 11.6°C | 11.7°C | 11.6°C | 12.5°C | +1.6°C |
| Avg High | 12.9°C | 13.7°C | 13.6°C | 13.5°C | 14.6°C | +1.7°C |
| Avg Low | 8.9°C | 9.4°C | 9.8°C | 9.6°C | 10.4°C | +1.5°C |
| Avg Rain | 60 mm | 56 mm | 84 mm | 69 mm | 73 mm | +13 mm |
May temperatures in Llanelli have risen by about 1.9°C between 1981–1985 and 2021–2025.
May has ranged from a record low of 4°C (1996) to a record high of 22.1°C (1989).
Rainfall in May is one of the drier months, averaging 68 mm, with a wettest year of 180 mm.
A good time to visit Llanelli
May is a good time to visit Llanelli, with days averaging 13.6°C and nights around 9.5°C (mean 11.6°C, close to Llanelli's yearly average) and moderate rainfall. August and July 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 🔥 | 15.8°C | 13.5°C | 11.2°C | 19.5°C | 7.2°C | 40 mm | 82% | 3.8 m/s | 6.1 |
| 2024 | 15.2°C | 13.1°C | 11.1°C | 18.5°C | 8.0°C | 98 mm | 85% | 3.6 m/s | 5.1 |
| 2023 | 15.0°C | 12.6°C | 10.3°C | 17.4°C | 8.8°C | 38 mm | 85% | 3.7 m/s | 6.2 |
| 2022 | 14.4°C | 12.6°C | 10.8°C | 17.4°C | 9.2°C | 64 mm | 87% | 3.9 m/s | 5.6 |
| 2021 🌧️ | 12.2°C | 10.6°C | 9.1°C | 17.3°C | 5.2°C | 180 mm | 82% | 4.8 m/s | 5.6 |
| 2020 | 14.8°C | 12.3°C | 9.7°C | 19.9°C | 5.3°C | 16 mm | 80% | 4.1 m/s | 6.5 |
| 2019 | 13.5°C | 11.5°C | 9.4°C | 15.5°C | 6.3°C | 42 mm | 82% | 3.6 m/s | 5.9 |
| 2018 | 14.6°C | 12.3°C | 10.0°C | 20.4°C | 6.9°C | 58 mm | 84% | 2.9 m/s | 5.5 |
| 2017 | 14.6°C | 12.5°C | 10.3°C | 19.3°C | 7.4°C | 56 mm | 86% | 3.8 m/s | 5.4 |
| 2016 | 14.3°C | 12.1°C | 9.9°C | 17.3°C | 7.2°C | 72 mm | 85% | 3.6 m/s | 5.5 |
| 2015 | 12.5°C | 10.9°C | 9.4°C | 15.3°C | 7.1°C | 122 mm | 84% | 5.3 m/s | 5.5 |
| 2014 | 13.8°C | 12.1°C | 10.4°C | 16.0°C | 8.2°C | 83 mm | 85% | 4 m/s | 5.4 |
| 2013 | 11.8°C | 10.0°C | 8.1°C | 15.0°C | 5.9°C | 83 mm | 84% | 5 m/s | 5.7 |
| 2012 | 13.5°C | 11.4°C | 9.4°C | 20.4°C | 5.8°C | 69 mm | 84% | 3.7 m/s | 5.4 |
| 2011 | 13.4°C | 11.8°C | 10.2°C | 15.5°C | 7.1°C | 62 mm | 84% | 6.1 m/s | 5.3 |
| 2010 | 13.1°C | 11.0°C | 8.8°C | 19.7°C | 5.8°C | 41 mm | 83% | 3.4 m/s | 5.8 |
| 2009 | 13.3°C | 11.5°C | 9.7°C | 19.3°C | 7.0°C | 62 mm | 85% | 5.1 m/s | 5.4 |
| 2008 | 14.9°C | 12.6°C | 10.4°C | 19.7°C | 8.0°C | 76 mm | 85% | 3.9 m/s | 4.9 |
| 2007 | 13.7°C | 12.0°C | 10.3°C | 16.3°C | 8.3°C | 121 mm | 84% | 5 m/s | 5.5 |
| 2006 | 13.2°C | 11.4°C | 9.6°C | 17.9°C | 7.9°C | 128 mm | 87% | 4.6 m/s | 4.9 |
| 2005 | 12.8°C | 11.0°C | 9.1°C | 17.6°C | 6.1°C | 45 mm | 83% | 4.9 m/s | 5.8 |
| 2004 | 13.9°C | 11.9°C | 9.8°C | 18.6°C | 7.0°C | 47 mm | 85% | 3.2 m/s | 6.1 |
| 2003 | 13.1°C | 11.6°C | 10.1°C | 20.1°C | 8.0°C | 83 mm | 84% | 5.1 m/s | 5.2 |
| 2002 | 13.2°C | 11.5°C | 9.7°C | 17.3°C | 6.8°C | 140 mm | 84% | 5.3 m/s | 5.3 |
| 2001 | 14.3°C | 11.9°C | 9.5°C | 18.9°C | 5.8°C | 43 mm | 85% | 3.5 m/s | 5.7 |
| 2000 | 13.8°C | 11.7°C | 9.5°C | 18.5°C | 7.3°C | 90 mm | 85% | 4.3 m/s | 5.3 |
| 1999 | 14.1°C | 12.4°C | 10.6°C | 17.4°C | 8.2°C | 53 mm | 87% | 4.6 m/s | 4.7 |
| 1998 | 14.9°C | 12.6°C | 10.3°C | 19.6°C | 6.8°C | 31 mm | 85% | 4.1 m/s | 5.8 |
| 1997 | 14.0°C | 11.7°C | 9.4°C | 18.4°C | 4.4°C | 69 mm | 84% | 4.4 m/s | 5.8 |
| 1996 ❄️ | 11.6°C | 9.5°C | 7.3°C | 15.8°C | 4.0°C | 103 mm | 80% | 5 m/s | 5.4 |
| 1995 | 13.4°C | 11.3°C | 9.2°C | 20.5°C | 5.6°C | 52 mm | 81% | 4 m/s | 5.4 |
| 1994 | 12.8°C | 10.9°C | 9.0°C | 15.4°C | 6.4°C | 61 mm | 83% | 4 m/s | 5.2 |
| 1993 | 13.2°C | 11.1°C | 9.0°C | 17.6°C | 5.8°C | 126 mm | 83% | 5 m/s | 4.8 |
| 1992 | 14.7°C | 12.3°C | 10.0°C | 19.8°C | 7.1°C | 34 mm | 84% | 4.2 m/s | 5.8 |
| 1991 | 13.2°C | 11.0°C | 8.8°C | 16.2°C | 5.6°C | 11 mm | 84% | 3.8 m/s | 5.4 |
| 1990 | 15.3°C | 12.7°C | 10.2°C | 21.4°C | 8.3°C | 25 mm | 81% | 3.3 m/s | 5.8 |
| 1989 | 15.3°C | 12.7°C | 10.1°C | 22.1°C | 7.1°C | 11 mm | 83% | 3.3 m/s | 5.9 |
| 1988 | 13.6°C | 11.5°C | 9.4°C | 17.8°C | 8.0°C | 61 mm | 84% | 4.2 m/s | 5.7 |
| 1987 | 12.5°C | 10.5°C | 8.5°C | 16.4°C | 5.9°C | 34 mm | 83% | 4.6 m/s | 5 |
| 1986 | 11.7°C | 10.1°C | 8.5°C | 14.8°C | 6.5°C | 78 mm | 86% | 5.7 m/s | 5.1 |
| 1985 | 12.9°C | 10.8°C | 8.6°C | 16.7°C | 6.0°C | 47 mm | 83% | 3.8 m/s | 5.5 |
| 1984 | 12.8°C | 10.4°C | 8.1°C | 15.7°C | 5.3°C | 46 mm | 81% | 4.1 m/s | 5.6 |
| 1983 | 11.6°C | 9.9°C | 8.2°C | 14.7°C | 5.2°C | 106 mm | 86% | 4.4 m/s | — |
| 1982 | 13.1°C | 11.0°C | 9.0°C | 17.4°C | 5.3°C | 36 mm | 82% | 4 m/s | — |
| 1981 | 12.7°C | 11.0°C | 9.3°C | 15.6°C | 6.5°C | 117 mm | 87% | 4.7 m/s | — |
Actual recorded May data for each year, 1981–2025 — sourced from NASA POWER.
The average high in May is around 13.6°C with lows near 9.5°C (mean 11.6°C), based on 45 years of NASA POWER data.
May averages 68 mm of rainfall in Llanelli, one of the drier months. The wettest on record was 180 mm in 2021.
The hottest May reached 22.1°C in 1989. The coldest dipped to 4°C in 1996.
Comparing the earliest years on record (1981–1985) with the most recent (2021–2025), average May temperatures have risen by about 1.9°C. Daytime highs moved from 12.6°C to 14.5°C and overnight lows from 8.6°C to 10.5°C over the same span.
May is close to Llanelli's year-round average and one of the drier months, so plan for around 13.6°C daytime highs and 9.5°C at night.
Not quite — May is the 7th coolest month in Llanelli, averaging 11.6°C.
For May in Llanelli, pack light layers you can adjust through the day, with typical highs of 13.6°C and lows of 9.5°C. Bring an umbrella or light rain jacket too.
Relative humidity in May averages 84% — quite humid.
Average wind speed in May is 4.3 m/s. The windiest May on record averaged 6.1 m/s (2011).
The wettest May on record was 2021 with 180 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 Llanelli 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.
