Thunderstorm Safety and Preparedness
By Linda Lam
7 days ago
At a Glance
- Tropical development typically arrives in June.
- The threat of severe weather shifts north and the concern for flash flooding increases.
- Temperatures heat up across most of the United States, but June gloom is expected in parts of California.
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June brings a notable shift from spring to summer and several weather changes to watch for across the United States.
Here are five things that typically happen in June:
1. Atlantic Hurricane Season Officially Begins
Atlantic hurricane season officially starts in June, although it's typically one of the quieter months of the season.
On average in the Atlantic Basin, one named storm forms every one to two years in June and a hurricane develops about once every five years.
(MORE: Here's What Is Typical In June In Atlantic Hurricane Season)
In 2023, three tropical storms - Arlene, Bret and Cindy - formed, but only Bret had at least some modest rain and wind impact in the Lesser Antilles.
Three years ago, four storms formed (Bill, Claudette, Danny and Elsa), the most in any June during the satellite era, since the mid-1960s.
Early in the season, tropical storms most often form close to the U.S. and often affect the Southeast and/or the western Caribbean. Rain, rather than wind, is usually the biggest concern with June tropical cyclones.
(Further beef up your forecast with our detailed, hour-by-hour breakdown for the next 8 days – only available on our Premium Pro experience.)
2. Tornado Threat Shifts Northward
June is typically an active month for tornadoes, the third busiest month by number over the past 20 years, behind only May and April. They can happen just about anywhere in the Lower 48, given the widespread warmth and humidity.
The area at highest risk of tornadoes in June stretches from Oklahoma into southwestern Minnesota.
In the Southeast, June tornadoes tend to be fewer, either along sea-breeze collisions closer to the coast or associated with landfalling tropical storms.
Peak hail activity also occurs in June, according to some studies. The Central and Southern Plains see an increase in hail during the early summer due to the increasing supply of hot and humid air.
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3. Thunderstorms, Lightning And Flash Flooding Increase
Warm, humid air expands its reach in June, increasing the threat of pop-up thunderstorms in much of the East, South and Midwest. Clusters of thunderstorms, also called Mesoscale Convective Systems (MCS), often track across portions of the Central Plains into the Ohio and Tennessee valleys, especially from evening through the early morning hours.
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All these thunderstorms pose a danger of lightning strikes. June has the third-most lightning-related deaths over the past 10 years.
June thunderstorms are often efficient rain producers. Slower-moving weather systems, the emergence of tropical systems and the kickoff of the wet phase of the Southwest monsoon can all wring out heavy rain and flash flooding.
4. Temperatures Heat Up
Temperatures and humidity levels continue to climb toward their peak later in summer in much of the U.S.
In early June, average high temperatures from Boston to New York are in the 70s and rise into the 80s by the end of the month. The average low in Washington, D.C. on June 1 is 63 degrees and climbs to 71 by June 30.
Chicago and Minneapolis experience average highs in the mid-70s in early June and reach the mid-80s by the start of July. Average lows are in the mid-60s for much of the Midwest by late June.
Dallas experiences average highs in the mid-90s by the end of June. Lows in the 70s are common by the end of the month across most of the South.
The average high in Denver jumps by 10 degrees during June and the average low rises from 49 to start June, to 57 on June 30. The average high by the month's end is 107 degrees in Phoenix and 91 in Sacramento, with average lows of 83 and 58, respectively.
(MORE: Here's When The First 90-Degree Highs Typically Happen)
5. Where June Is Gloomy
"June gloom" occurs when the temperature drops and low clouds and fog move ashore during the morning hours in parts of Central and Southern California.
Cold, more humid air comes from the chilly ocean current that can be pushed onshore due to a pressure difference between high pressure off the California coast and a thermal low that develops inland due to intense heating.
Low clouds form and are pushed onto the beaches. This so-called marine layer can be deep enough at times that light rain showers develop.
These clouds usually clear by early afternoon as heating from the sun erodes the cold oceanic air.
MORE ON WEATHER.COM
- Hurricane Terms You Need To Know
- Why Weather Slows Down In Summer
- Tropical Destinations Where Hurricanes Are Less Likely
Linda Lam is a lead meteorologist at weather.com. Growing up in Massachusetts she developed a fascination for winter storms and hurricanes that led her to pursue a career in meteorology.
