Las Vegas Got More Than a Third of its Annual Rainfall in Just Four Days

It’s only the first week of the month and Las Vegas has already recorded its wettest May on record after a storm system delivered rain to the city for four days straight. In the Las Vegas suburb of Henderson, a man was swept away by floodwaters on Tuesday.

The rains, considered rare for this time of year, came after a big low-pressure system dropped from the north down into the Mojave Desert, which includes southeastern California, southwestern Nevada and small portions of Arizona and Utah. The system hunkered down over the region and intermingled with moisture flowing in from the Pacific Ocean.

“It was kind of unusually placed over the Mojave Desert, and it was very slow to move out,” said Chris Outler, a meteorologist with the National Weather Service in Las Vegas. “It’s very unusual.”

May is typically the second-driest month in the Mojave, which usually gets most of its rainfall during the summer monsoons and winter months. But from Saturday through Monday it saw persistent rain, and on Tuesday thunderstorms delivered heavy downpours, strong winds and hail up to the size of quarters. On Tuesday, the Weather Service issued multiple warnings for severe thunderstorms across the eastern Mojave Desert, from east San Bernardino County in California into the Las Vegas area and all the way east into Bullhead City, Ariz.

In records dating to 1937, a Weather Service rain gauge at Harry Reid International Airport in Las Vegas recorded four days of consecutive rain, something it had never done before in May. By Tuesday, it had recorded 1.44 inches, marking the wettest May ever and beating a previous record of 0.96 inches set in 1969.

To put this in perspective, in a typical year, Las Vegas receives about 4.18 inches of rain. It received more than a third of that in just four days.