Key Headlines
- A severe weather outbreak over the weekend of May 15-18 resulted in three EF3 tornadoes and one EF4 tornado, causing significant damage in Kentucky, Missouri, Illinois and Arkansas.
- The outbreak is likely the costliest severe weather event of 2025, with extensive damage to residential and commercial properties, as well as infrastructure.
- As of mid-May, 731 tornados have been reported, nearing the record for this time of year and indicating a season well above average in terms of activity.
- Severe weather activity is expected to persist through mid-June, which is typically the peak of severe weather season in the United States.
Meteorology
May 16 saw a low-pressure system form over eastern South Dakota and upper Minnesota. Throughout the day the system tracked east, dragging a series of cold fronts across the Ohio Valley region. These cold fronts pushed into a region of warm and moist air, and enough instability was present to fuel a severe thunderstorm outbreak. Accompanying this setup was deep-layer shear, or winds changing direction with height, a key ingredient for severe weather and tornadoes.
Ahead of the storm system, the Storm Prediction Center (SPC) issued a Moderate (level 4/5) risk over the Mid-Mississippi and Ohio Valley/Tennessee Valley Region, with strong winds, large hail, and tornado outbreaks expected throughout the warning areas. The SPC also noted the likelihood of strong tornadoes (EF3+) was highest through the Moderate and Enhanced risk areas. This was unfortunately validated, as three EF3 tornadoes and one EF4 tornado were reported out of this system.
Impacts
The tornado outbreak in the Midwest and Southeast has resulted in significant economic and insured losses, likely making it the costliest severe weather loss event of 2025 so far. The storms, which included at least 33 tornadoes, caused extensive destruction in Kentucky, Missouri, Illinois, and Arkansas. Thousands of buildings in St. Louis were damaged, and more than 600,000 customers were without power across the affected region. Major urban areas were hit, with both residential and commercial properties suffering financial damage.
Prior to this weekend’s event, the US was already seeing above-average straight-line wind and tornado activity. In some communities, entire neighborhoods and key infrastructure, such as airport hangers and emergency service buildings, sustained significant structural damage from this event.
Damages from this event will likely put the season above average in terms of insured losses. The economic impact extends beyond insured losses, as uninsured damages, business disruptions, and infrastructure repairs will contribute to the overall cost of recovery. Insurers will be evaluating premium adequacy and underwriting standards in high-risk areas as a result of the high losses from this event.
Looking back at historical data, since 1990, there have been 25 severe convective storm events that have resulted in losses of $4 billion or more, adjusted for inflation. Most of these events fall between $4 billion and $6 billion in losses, with about a quarter exceeding the $6 billion threshold. Four of the five most damaging events have been driven by tornadoes, with the 2020 Midwest Derecho being the highest loss event in the United States. Missouri often experiences significant losses from severe storm events, with four of the top 25 events primarily driven by losses within the state.
Seasonal Outlook
Tornado activity across the United States has been well above average in 2025. As of May 18, 731 tornadoes have been recorded, just shy of the all-time maximum for the date. Hail and wind reports are also well above the 2005-2015 means. Most of the activity has been located across the Mid-Mississippi River Valley, east of the traditional “Tornado Alley” over the Great Plains. This easterly shift of severe weather in 2025 remains consistent with decadal trends of severe thunderstorm activity.
Additional severe weather continued through May 19, though damages were markedly less than previous days. Significant severe weather activity is likely to continue through June, which marks the climatological end of peak severe thunderstorm activity across the central US.