Weather data recording started in Penallt in March 2011. The charts below show the monthly summaries from January 2021 until the end of December 2021 and also compare Penallt’s 2021 weather with the 1981-2010 overall average data for Usk, the nearest place (16 km by crow) for which reliable data exist.
Monthly maximum and minimum temperatures
The chart shows that Penallt monthly averages mirrored the long term averages for Usk pretty well overall, with April and May being much cooler than usual, and only August being significantly warmer.
Penallt was clearly warmer by night overall, perhaps due to temperature inversion effects.
- July 20th was the warmest day of the year with a maximum of 30.5°C
- January 25th had the lowest maximum temperature of -0.3°C; it was the only day with sub zero all day.
- Warmest by night was July 20th with a minimum of 24.4°C
- Coldest by night was January 7th, with a minimum temperature of -4.7°C
- There were 72 days on which the temperature exceeded 20°C and 39 when it was below 0°C
- The mean annual temperature was 10.4°C.
The mean annual temperature for England and Wales (1845 to 2012) is 9.3°C. The 2021 figure for Penallt is thus 1.1°C above the England/Wales average. Whilst maximum temperatures were only above Usk means in three months, night times were much warmer than usual, being higher than usual in all bar March and July (when the differences were small).
The chart shows the usual uneven distribution of rainfall throughout the year. Three months had in excess of 100 mm falling, with May’s 185.4 mm being the wettest. By contrast, November was an untypically dry month (15.2 mm)
Overall, the total rainfall for 2021 was 938.8 mm (37.0 inches), 87% of the average Usk total of 1076.9 mm (42.4 inches) showing that the year was drier than average overall and making it the second driest year since April 2011, only beaten by 2019 (933.2 mm).
- Rain was recorded on 204 days in the year
- The wettest day was May 13th when 33.2 mm fell
- 20 mm or more fell on 11 different days
Much more information about month by month descriptions of weather in this year as well as the detailed daily data is available here.