An historical perspective of the climate statistics

for Coventry during April 2021

Temperature

Mean monthly April temperatures did not vary much in the 20th century in Coventry, averaging 8.2C, ranging from 7.6C in the 1970s, up to 8.9C in the 1940s and 1990s.

There are signs of some considerable warming however during April in the 21st century in our region, with mean monthly temperatures averaging 9.5C (2001-2020), an increase of 1.3C, with only 4 April months recording below average temperatures (1971-2000) since 1989.

So, April 2021 has come as a bit of a shock, with temperatures averaging just 6.7C, 2.6C colder than 30-year averages 1991-2020. It has been the coldest April in Coventry since 1986 (6.3C).

After last year’s April warmth (10.9C), April 2021 has been 4.2C colder than in 2020.

With records dating back to 1892, only 6 April months have been colder than this year, namely 1908, 1917, 1922, 1941, 1978 & 1986).

It was a frosty month, with 9 air frosts & 23 ground frosts, both becoming the highest incidence of frost in Coventry since 1917 (13 and 24 respectively).

April 2012 has been colder (6.7C) than March (7.3C); though not exactly a rare occurrence, this is the first time since 2012, and it has only happened 8 times since 1892 (1903, 1957, 1978, 1981, 1989, 1991, 1998 and 2012).

The first four months of 2012 have averaged 5.5C, making this the coldest first January to April spell in Coventry since 2013, with only four colder spells in the first third of the year since 1991 (1996, 2001, 2010 & 2013).

21stThe mildest night registered a minimum of just 6.8C, the lowest such value since 1989 (6.6C).

7thThe lowest grass minimum temperature measured -7.4C, the lowest in April since 2013 (-8.6C), the only grass minimum lower than this year in the past 30 years.

Rainfall

There was quite a lot of variation in mean monthly rainfall totals in Coventry in the 20th century, ranging from 33.6mm in the 1950s, up to 60.2mm by the 1990s. There has been a 25% decrease however, in April’s average monthly rainfall since the Millennium compared to the latter years of the last century.

This is a trend much in evidence with April 2019 (28.2mm) and April 2020 (28.8mm) recording rainfall totals well below average, though April 2021 has been even drier with just 16.4 mm of rain, 34% of 30-year Bablake rainfall averages 1991-2020.

Looking back through the archives, we find that –

only 3 April months have been drier than this year since 1974, that is in the past 47 years (1984, 2007, 2011).

In records dating back to 1892, April 2021 ranks 8th wettest in Coventry in the past 151 years.

There was a meteorological drought from 12th to the 26th, making this the longest April dry spell (15 days) since 2011 (16 days).

27ththe wettest day of the month ended the drought with 14.6mm of rain, 89% of the monthly rainfall total in just one day.

There were 4 days with snowfall during April 2010, the highest incidence of snow days in the city since 2016 (5 days).

Sunshine

It would appear that the average April sunshine total in Coventry is now 15% higher than one hundred years ago, and 24% higher since the Millennium (170.0hr) than in the 20th century (137.0hr). It is far too easy to explain this increase in April sunshine by putting it down to the Clean Air Acts of the 1950s and 1970s, especially as there was a notable decrease in April sunshine between 1961 and 1980, by as much as 20%.

April 2021 recorded 211.5hr of sunshine (133% of average), the second April in a row to record more than 200 hours of sun (2020=242.0hr); only 3 April months have had more sunshine since 1990, and 7 since 1895.

April 2021 has been an anticyclonic month, averaging 1023.5mb, the highest mean sea level pressure since 1983.

It was also a month dominated by light winds, averaging 6.1mph; this is the lowest mean April wind speed in Coventry since 1990 (5.5mph).