Pennsylvania sees at least two tornadoes each June as the conditions needed for tornadoes increase across most states.

Weather in your inbox

Forecast Location

Sign Up

By signing up you agree to the Terms & Privacy Policy. Unsubscribe at any time.

Although May is the peak month for tornadoes in the United States, June has no shortage of notable tornadoes. They range from the Plains eastward to Pennsylvania and Massachusetts.

(MORE: Tornado Central)

June's Tornado History

Large outbreaks are not as common as in May or April, but they can happen. Outbreaks with EF4 and EF5 tornadoes can also happen in June. On average, an EF5/F5 tornado occurs in June once every seven to eight years and at least one EF4/F4 tornado occurs each year.

A tornado outbreak with at least 20 tornadoes swept across Pennsylvania on June 2, 1998. Two people were killed by tornadoes as storms rolled southeastward across the state during the evening hours.

An F3 tornado which touched down near Scranton caused both fatalities that night and added $2.2 million in damages to a 26-mile stretch of land. More than 90 violent tornadoes have occurred in June since 1950.

On June 3, 1980 – the 'Night of the Twisters' in Nebraska – an F4 tornado struck with a separate batch of storms on the outskirts of Pittsburgh, Pennsylvania. The tornado caused at least $50 million in damage and injured 140 people.

Worcester, Massachusetts, was heavily damaged by an F4 tornado on June 9, 1953. At least 90 people were killed as this mile-wide tornado destroyed 35 miles of real estate and injured more than 1,000 people. This tornado was partially responsible for reorganizing the Storm Prediction Center into what it is today.

A deadly tornado outbreak took place June 2, 1990, across portions of the Midwest and Ohio Valley. Through the early morning of June 3, 65 tornadoes developed, 37 of which occurred in Indiana. In addition, seven were F4 tornadoes.

Another noteworthy tornadic event took place just four years ago, when twin tornadoes developed in Pilger, Nebraska, on June 16, 2014. Two distinct large, strong and long-lasting tornadoes were in progress at one time, creating an unusual sight. This was the result of extreme instability in the area, which can arise in June.

A few metro areas see a peak in tornadoes during June, according to severe weather expert Dr. Greg Forbes.

This includes Chicago, which has seen 16 tornadoes in June during this time period, while May is a distant second, with nine recorded. As the jet stream migrates northward through the spring and early summer, Chicagoland becomes a more favorable area for tornadoes.

(MORE: Most Tornado-Prone Counties in the U.S.)

Denver is another city where the most tornadoes have been recorded in June, with 108 occurring in the four counties of Denver, Arapahoe, Adams and Jefferson. July comes in second with 87 tornadoes recorded.

June is also the busiest month for recorded tornadoes in Miami-Dade County. From 1950-2013, 27 tornadoes have been confirmed here in June. Spring and summer are active with thunderstorms in southern Florida; at least a dozen tornadoes have occurred from May through September in the Miami area.

Where Tornadoes Occur Most Frequently in June

In June, areas from central Oklahoma into southern Minnesota see the highest risk for tornadoes. The risk also increases from eastern North Dakota into Wisconsin, Michigan and as far east as Pennsylvania.

The threat of tornadoes also increases some in southern Florida in June, compared to earlier in the year, as the heart of the wet season kicks in.

The tornado risk remains elevated for a large swath from Texas into the central Plains, as well as from central and northern Illinois into Ohio.

In the Southeast, the overall tornado threat in the Southeast diminishes slightly as the jet stream begins to migrate northward. On the other hand, concern for waterspouts along the coast increases.

(MORE: Different Types of Tornadoes)

It's also important to note that tornadoes can occur outside the areas shaded in red, and it is always a good idea to be aware of weather conditions, especially when participating in outdoor activities. Only two states did not record a tornado in June from 1994 to 2013: Rhode Island and Hawaii.

Even though tornadoes can occur any time of the year, April, May and June are typically the peak months.

On average, based on data from 1996 through 2015, June has seen the second-most tornadoes, with more than 200 each year. Over the past three years, 185 tornadoes have been confirmed in June, second only to May, according to the Storm Prediction Center.

April through June is the time of year climatologically when ingredients for severe weather, including tornadoes, are most likely to come together.

(VIRTUAL REALITY: Experience the Formation of a Tornado)

One of these ingredients is a strong jet stream, which is typical across the central and northern Plains into the Midwest in June. Other factors include surface dew points in the 60s or 70s and increasingly hot temperatures.

The moisture and warmth provide the fuel for thunderstorms, while the jet stream provides wind shear, or changing wind speed and direction with height to sustain either supercell thunderstorms or long-lived thunderstorm clusters.

When the jet stream digs southward with an area of low pressure, this helps to instigate the development of thunderstorms, which can become severe and spawn tornadoes when the above ingredients are in place.