Weather data recording started in Penallt in March 2011. The charts below show the monthly summaries from January 2020 until the end of December 2020 and also compare Penallt's 2020 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 warmer than usual, and July and October being significantly cooler.
- August 12th was the warmest day of the year with a maximum of 33.2°C
- December 28th had the lowest maximum temperature of 1.9°C; there were no days with sub zero all day.
- Warmest by night was August 12th with a minimum of 19.7°C
- Coldest by night was December 31st, with a minimum temperature of -2.8°C
- There were 75 days on which the temperature exceeded 20°C and 17 when it was below 0°C
- The mean annual temperature was 10.7°C, equal to the 2014 and 2018 record warm years.
The mean annual temperature for England and Wales (1845 to 2012) is 9.3°C. The 2019 figure for Penallt is thus 1.4°C above the England/Wales average. Whilst maximum temperatures were only above Usk means in four 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. Six months had in excess of 100 mm falling, with December's 257.4 mm being the wettest. By contrast, May was a remarkably dry month (6.2 mm)
Overall, the total rainfall for 2017 was 1345.6 mm (53.0 inches), 25% above the average Usk total of 1076.9 mm (42.4 inches) showing that the year was wetter than average overall and making it the third wettest year since April 2011, only beaten by 2012 (1575.5 mm) and 2014 (1508.1).
- Rain was recorded on 222 days in the year
- The wettest day was December 23rd when 54.8 mm fell - the third highest since records began in April 2011
- 20 mm or more fell on 18 different days
See synopses page for individual links to monthly data.