It is Severe Weather Awareness Week in Ohio, and despite the benign weather, longer days and warmer temperatures mean that thunderstorms will soon impact our area.

Many of you have probably heard of the phrase “bolt from the blue” which refers to a lightning strike that occurs some distance from a thunderstorm. Is it actually possible for lightning to strike during clear conditions?

The longest distance that lightning can strike from a thunderstorm is typically between 10-12 miles. However, lightning has been reported farther away than 12 miles from the storm, but this is extremely rare.

Typically, bolts from the blue occur when a lightning strike exits that back side of an isolated thunderstorm. The strike moves out of the cloud and into clear air where it will usually strike a tall object such as a tree, radio tower, etc. The video below shows what a bolt from the blue looks like.

Bolt from the blue from an Illinois thunderstorm.

In other words, a lightning strike with clear skies is possible. These lightning strikes can be deadly because people typically do not take shelter with clear skies overhead because they think the lightning cannot harm them. Here is a good piece of advice: When thunder roars, go indoors. If you can hear thunder, then the lightning is close enough to strike you.

When is lightning most common in the Valley?

While lightning has occurred in March before, it is not common. The frequency of lightning strikes begins to increase around the second week of May. The majority of lightning strikes recorded in early May occur in the late night and early morning hours. This is likely due to afternoon storms that formed in parts of Illinois/Indiana that are sliding into the area at night. You can view the total amount of cloud-to-ground lightning flashes within 10 miles of the Youngstown/Warren Regional Airport below.

You can view a more zoomed-in version of the image using NOAA’s lightning climatology.

Weekly by hour total cloud-to-ground lightning flashes between 1988 and 2017 within 10 miles of the Youngstown/Warren Regional Airport.

Each block represents a week’s worth of lightning data at a certain time. For example, if you click on the 732 number, you can see that there have been a total of 732 cloud-to-ground flashes observed between 1988 and 2017 in the week of May 7 to May 13 between 10 and 11 p.m.

732 cloud-to-ground flashes were observed between 1988 and 2017 during the week of May 7 and May 13.

Climatologically speaking, the week with the highest cloud-to-ground lightning frequency is between July 23 and July 29 in the Youngstown area. In total, there have been 90.2 thousand cloud-to-ground strikes over the 29-year period.

The frequency of lightning is active in Youngstown between May 1 and Oct. 1 and then drops significantly as colder air arrives.