For the first time in 84 years, a tropical storm has made landfall in California. Hurricane Hilary, with maximum sustained winds of 130mph (210km/h) and a central air pressure of 943mb, advanced towards the Baja California peninsula this weekend as a category 4 hurricane, before weakening and arriving as a tropical storm in southern California late on Sunday.
Tropical storms are less strong than hurricanes and have maximum sustained winds below 74mph, while hurricanes are at or above this speed. The last time a tropical storm made landfall in southern California was in 1939, when it flooded Los Angeles and killed nearly 100 people.
Hilary triggered California’s first ever tropical storm warning, extending from the Mexican border to just north of Los Angeles amid rainfall totals estimated to have reached 70-150mm (3-6in) across southern California. This amount of rainfall is expected to cause life-threatening flooding, and would amount to more than a year’s worth of rain across parts of California and Nevada.
Joe Biden announced last week that the Federal Emergency Management Agency had positional personnel and supplies to respond across the region, and the Mexican army deployed nearly 14,000 soldiers to the city of Mexicali and the states of Baja California Sur, Jalisco and Colima.
Hilary will gradually weaken into a depression as it progresses north-northwestwards through California, Nevada, Oregon and Idaho during the early part of this week, although still bringing heavy rain to these parts. Central and south-west Idaho usually only have about 15mm of rainfall for August, but could receive cumulative totals of 30-50mm through the next few days.
Meanwhile, large parts of the midwest and the central and southern plains of the US have been put under excessive heat warning going into this week as temperatures continue to soar 5-10C above the climatological average. Last Friday, more than 65 million people were put under these heat alerts, with many warnings extending into Friday or Saturday this week. Widespread temperatures over 38C (100F) are probable through this week but with peak temperatures reaching the low to mid-40Cs (104-112F) in places.
In Europe, more heat will be moving up from northern Africa this week. Spain and Portugal will be most affected, with south-west Spain and southern Portugal seeing temperatures reaching the low 40Cs. Parts of Italy and southern France can also expect temperatures of about 40C. However, this heat should subside as low pressure brings cooler westerly winds towards this weekend.
• This article was amended on 22 August 2023. An error introduced during editing described Hilary as a tropical storm while travelling towards the coast. In fact, at this point in her journey, she was still a hurricane; it was only shortly before landfall that she weakened and turned into a tropical storm.
