Throughout much of central and Pacific Costa Rica, the weekend could be described in a word: wet.

Today the National Meteorological Institute forecasts possible scattered showers too. Tomorrow and Wednesday, said the weatherwoman Gabriela Chinchilla, could see heavy rains similar to the weekend, all unusual for this time of year.

It rained Friday, heaviest in the northernmost reaches of the northwest Guanacaste province, according to Chinchilla. Friday also saw rainfall in the Central Valley and the central and southern Pacific regions.

Storms came suddenly in the afternoon and caused at least one death. Esteban Vega, 14, was struck and killed by lightning while he was riding his bicycle in the southern Costa Rican town of Buenos Aires, news media reported. The lightning, according to the daily Al Día, struck him before it began to rain.

Saturday it rained heavily again, particularly in Cartago (east of San José ), causing sewers there to overflow and homes to flood, Chinchilla said.

And Sunday saw a downpour akin to those more characteristic of Costa Rica's green season, or invierno (winter), as it's known locally. There were again electrical storms and even hail in the mountains of Heredia, north of San José, causing some power outages.

Is this a sign, residents may ask, of an early invierno – already in April?

Chinchilla says, yes, and it's early as predicted. The “transition” started at the beginning of the month, whereas she said it normally starts sometime in the first two weeks of May. La Niña is the culprit, meteorologists say, and predict the phenomenon will continue through June or July.

Chinchilla said the green season will begin sometime between April 16 and 20 in the Central Valley and Central Pacific, and from April 26 to 30 in Guanacaste.