First summer heat wave will bring up to 40C to Castellón ahead of San Juan

Heat wave arrives before San Juan

Castellón is entering the first major heat wave of the summer just as the San Juan celebrations approach, with forecasts pointing to highs of up to 40C in parts of the province.

Local reporting on June 21 said the episode would intensify on June 22 and June 23, making the nights around San Juan unusually warm and increasing concern about both health impacts and wildfire risk.

The event is part of a broader heat wave affecting Spain. National coverage of AEMET’s special warning said the episode began on June 21 and was expected to reach its most intense phase on June 23.

What is expected in Castellón

The strongest heat in Castellón is expected to arrive during the period between June 22 and June 23, with daytime temperatures near 40C and overnight lows remaining high enough to limit recovery from the daytime heat.

That matters because the hottest stretch overlaps with San Juan, one of the busiest early-summer festivities on the coast and across towns in the province, when outdoor activity typically increases.

AS linked the wider episode to a mass of hot, dry Saharan air and a DANA to the west of the Iberian Peninsula, with temperatures only expected to ease after June 24 or June 25.

Health and fire-risk warnings

The Valencian health department has already moved to reduce risk. Cadena SER reported on June 22 that Sanidad declared a medium heat-risk level in 21 municipalities in l'Alt Maestrat, Baix Maestrat and Els Ports.

Those alerts add to the public-health concern around the episode, especially for older people, children and others more vulnerable to heat stress.

The other major concern is fire. Regional and national coverage both stress that the combination of heat, dryness and warm nights raises the danger of wildfires in rural and inland areas.

Wider picture and next steps

The heat wave is not limited to Castellón. El País reported on June 22 that warnings were in place across 14 autonomous communities, with some inland and southern areas facing temperatures above 40C and reaching 42C in places.

For Castellón, the immediate question is how long the most intense phase will last and whether AEMET or health authorities adjust their warnings in the next updates.

The most closely watched period is June 22 to June 24, when the province is expected to see the sharpest heat, the most difficult nights and the highest need for caution around outdoor activity and any possible ignition sources.