Why does it rain so much in April?

“In April, thousands of waters”, most of us are familiar with this and other popular sayings that refer to the rains in the fourth month of the year, but why does it usually rain so much this month?

What science says

April is a month in transition; the long, cold winter days begin to subside, and bands of strong winds begin to move north. The coldness of the previous months is replaced by heat and light, but the pressure is too low and as a result the skies open. But there is more to the April rains than just low pressure. At this time of year, the sea temperature is at its lowest. Longer days and warmer weather result in a significant increase in daytime warming. And it is this disparity, between the warm land and the cold sea, that causes clouds to form that provide rain.

Climate graph // Weather by Month San Sebastian

The rainiest month?

April rains really do exist, which doesn’t make it the wettest month of the year, according to Statista. In 2018, more rains were registered in all the Spanish provincial capitals in the months of October and November, and in most of them also in the months of December and January, which leaves April far from being the rainiest month. Despite the enormous variation in rainfall between the Spanish provincial capitals, they all maintain this dynamic. From the rainiest, San Sebastián, with 185mm in December, 155mm in October and 130mm in April; even a much drier and geographically as distant as Seville, with 97mm in December, 62mm in October and 59mm in April.

Showers and showers

You have to be clear about one thing, and that is that rains and showers, scientifically, do not mean the same thing. Rain is precipitation that falls from a climate front, a boundary between two bodies of air. Often spanning hundreds of kilometers and comprising various types of clouds, these fronts give rise to precipitation that falls over wide areas, often over many days.

The showers, on the other hand, are produced by cumulus or vertically developing clouds. Despite its impressive appearance, its scale is dwarfed by that of a front and rainfall rarely lasts for more than a few hours. Simply put, April is not the wettest month in terms of overall rainfall. Sayings like “in April, thousands of waters” come more than the frequency of short and regular showers.