Billion-dollar weather disasters are soaring again this year. Here’s why.

The repeated, costly thunderstorm outbreaks fit into a trend toward more such incidents that are driving a surge in weather-related property damage and insurance payouts across the United States.

Experts link the uptick to growth and development patterns that place many more homes and businesses in the way of such storms. At the same time, they say certain atmospheric ingredients that fuel these storms are becoming more abundant because of human-caused climate change.

The onslaught of costly disasters so far in 2024 is concerning ahead of what meteorologists expect to be an extremely active hurricane season. Tropical storms and hurricanes tend to have enormous geographical footprints, leading to lofty price tags that can wreak havoc on regional economies. The summer can also produce wildfires, droughts and heat waves, floods and additional severe storms outbreaks that carry billion-dollar price tags.

There were 28 billion-dollar weather disasters last year, the most on record.

Which disasters have been most expensive?

Nine of the 11 billion-dollar disasters to date have been severe thunderstorms outbreaks that also unleashed destructive twisters (the other two were winter storms). The most expensive was an outbreak across the Plains and Midwest between March 12 and 14, which killed three people and netted $5.9 billion in damage.

Second place, however, happened between May 6 and 10 — when 165 tornadoes struck 23 states from South Dakota to Florida. The strongest, an EF4 on the 0-to-5 Enhanced Fujita intensity scale, ravaged the town of Barnsdall, Okla., killing two people. As storms progressed east May 7, a swarm of tornadoes tore through southern Michigan, prompting the issuance of the state’s first-ever tornado emergency. The entire multiday outbreak racked up $4.7 billion in losses.

May’s other billion-dollar disaster — the severe thunderstorm complex that hit Houston — came in as the ninth most expensive so far in 2024. It was a small but intense arcing band of thunderstorms, known as a derecho. It produced multiple tornadoes and straight-line winds in excess of 100 mph. Skyscrapers in downtown Houston lost windows in a scene reminiscent of that left by Hurricane Alicia, which made landfall south of Houston as a Category 3 on Aug. 18, 1983.

How 2024 so far compares with the past

The 11 billion-dollar disasters so far this year ties with 2020 and 2017 for second-most year-to-date. There were 14 by the end of May last year, but this year’s have been more expensive so far.

2021 produced the most expensive January to May period for weather disasters, incurring costs of $40.4 billion in losses, which is $15 billion more than this year thus far. The average damage for this point in the year is closer to $11 billion.

Why have so many disasters occurred?

It’s no secret that this year has been active tornado-wise. In fact, exactly 1,000 have been tallied so far. April and May were the second most active on record, falling just 70 tornadoes shy of 2011’s record.

Part of the reason? A stagnant jet stream pattern. The jet stream has persistently dipped over the Western United States, with cool, dry Canadian air spilling south over the Rockies. High pressure and a northward-surging jet stream in the East has allowed Gulf of Mexico warmth and moisture to build. But periodic insurgences of Western cold spilling east helped fuel a dramatic clash that resulted in robust storms.

The period from April 26 to the end of May in particular featured seemingly nonstop barrages of severe storms and tornadoes. A pair of violent tornadoes — the EF4 in Barnsdall and another in Greenfield, Iowa — ended a five-year May stretch without tornadoes this strong.

The National Weather Service Storm Prediction Center compiled some other notable statistics regarding the May storms:

• The tornado count of 476 was the fourth most on record for the month.
• It issued the eighth most tornado watches on record for May.
• It received 6,284 reports of severe weather, second most on record during May.
• May featured 22 days in which it drew a Level 3 out of 5 risk of severe weather somewhere in the United States, the most in any month on record (since 2014).

The same warm weather that fueled the storms helped push temperatures 2.1 degrees above average in the United States during May, the 13th-warmest on record. The spring overall (March through May) was the 6th-warmest on record.

The above-average temperatures in the United States are part of global pattern of abnormal warmth. May marked the 12th consecutive month during which average global temperatures were higher than all observations since 1850.

Jason Samenow and Scott Dance contributed to this report