Hundreds of firefighters on Friday were battling Spain's first major forest fire of the year, which has so far forced 1,500 people to evacuate their homes, officials said.
Despite several days of unusually warm weather, firefighters said the blaze was more typical of the hot summer months than the spring.
It began just after midday (1200 GMT) on Thursday near Villanueva de Viver, some 90 kilometres (55 miles) north of Valencia, and since then has raged out of control.
"We are unfortunately facing the first big fire of the year and it's happening out of season," Prime Minister Pedro Sanchez said on a visit to Brussels.
"Such fires so early in the year are just more evidence of the climate emergency that humanity is facing," he said.
A total of 450 firefighters backed by 22 aerial units have been deployed to fight the blaze, the Valencian regional government said on Twitter.
So far, 1,500 people have been evacuated from eight municipalities in the area, regional government spokeswoman Aitana Mas said, adding that the blaze had incinerated more than 3,000 hectares (7,400 acres) within a 30-kilometre perimeter.
"We are facing a fire that is more typical of summer," Manolo Nicolas, spokesman for the Castellon firefighters, told RNE public radio.
With the vegetation dried out by a lack of moisture in the atmosphere in recent months, and "large amounts of combustible" biomass in the forests, conditions are "perfect for such a fire", he said.
The area of greatest concern is Montanejos, a village popular for its natural pools and springs, and whose hotels, which were full of visitors, had to be evacuated as a precautionary measure, its mayor Miguel Sandalinas told RNE.
"Temperatures will reach 30 degrees Celsius (86 Fahrenheit) today," Sandalinas said, blaming climate change for what he described as July-style heat "in the middle of March".
Firefighters warned of added difficulties posed by "strong winds that are going to get stronger in the coming hours", with Nicolas saying they would "make it more difficult to extinguish" the fire.
In 2022, which was a particularly bad year for wildfires in Europe, Spain was the worst-hit country with nearly 500 blazes that destroyed more than 300,000 hectares, according to figures from the European Forest Fire Information System (EFFIS).