Heat wave hits California, with some areas topping 40°C in October

San Diego tops 40°C in October for the first time in 39 years

High pressure is strengthening over the western United States, while the jet stream, a strong westerly wind high in the atmosphere, is meandering far north. As a result, much of California has been under warm air, with temperatures of +20–24°C around 1,500 m above the ground.

On Saturday, the 3rd, the high reached 38.9°C in Los Angeles and 40.6°C in San Diego. San Diego's high was 25.6°C on Thursday, the 1st, so temperatures rose by 15°C in just two days. It was the first time since 1987, 39 years ago, that San Diego reached 40°C (104°F) or higher in October.

Heat wave expected to continue through midweek

Los Angeles also recorded 37.2°C on Sunday, the 4th. According to a forecast by Weathernews, temperatures of 35°C or higher are expected to continue through Wednesday, the 7th.

The average high for this time of year over the past 10 years is around 26°C, making current temperatures nearly 10°C higher.

U.S. weather authorities have issued an Extreme Heat Warning and are stepping up calls for people to remain alert to heatstroke.