Spain and Portugal are reeling from a massive, unexplained power outage that knocked out traffic lights, caused chaos on roads and in airports, and prompted both countries to declare a state of emergency.

According to Spain’s meteorological agency, AEMET, temperatures across the country were between 60 and 70 degrees Fahrenheit around the time of the power outages. By the end of the day, highs had climbed to between 82 and 87 degrees.

On Monday morning, millions of people across the Iberian Peninsula lost power. The cause of the outage is yet to be determined.