April showers: what are they and why is it so rainy in April?

We often think of April as a rainy month, but is it really the wettest? Here we explore the science of April showers, terminology and take a look at the average rainfall in the month of April. 

rainy day in Ireland

‘March winds and April showers bring forth May flowers.’ Most of us are familiar with the term, but how can April have so many showers and still be one of the year’s driest months?

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Here we explore the science of April showers, terminology and take a look at the average rainfall in the month of April.

The science behind April Showers

April is a month in transition; the long, cold winter days start to wane, and the jet stream – a band of strong winds – begins to move northwards. The chilliness of the dark months is replaced with warmth and light, but so too low pressure and, as a result, the skies open.

Multi Colored Umbrella With Raindrop Shower
Don’t get caught out in an April shower! (Getty)

But there is more to our April showers than just low pressure. At this time of year, the temperature of the sea is at its lowest. Lengthening days and warming weather result in a significant increase in daytime heating. And it is this disparity – between the warm land and cold sea – that causes shower clouds to form.

Clouds-cfae004

Why is it so rainy in April?

April showers really do exist. It may, therefore, be a little confusing to learn that it is one of the driest months of the year, according to Statista. In 2018, Statista recorded 133.5mm of rainfall in January, compared to just 86.3mm in April. And in August of the same year, the rain gages registered 84.9mm, just 1.4mm more than April. September, October, November and December 2018 all clocked higher rainfalls than April.

Indeed, look back at the data over the past four years and you’ll discover similar results.

Cumulonimbus cloud
Cumulonimbus cloud ©Getty

The science appears to contradict the data. Perhaps the reason for all this confusion lies in the terminology: rain and showers are not the same thing.


What is the difference rain and showers?

Rain

Rain is precipitation that falls from a weather front – a boundary between two bodies of air. Often stretching over hundreds of miles and comprising various cloud types, these fronts result in precipitation falling over wide areas, often for many days.

Showers

Showers, in contrast, are produced by cumulus or cumulonimbus clouds. In spite of their impressive appearance, their scale is dwarfed by that of a front, and precipitation will seldom last longer than a few hours.

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Final conclusion

Put simply, April is not the wettest month in terms of overall rainfall. The term April Showers comes from the frequency of short, regular showers.