CALIFORNIA (KTXL) — In August 2020, a dry lightning storm across Northern and Central California created the August, SCU and LNU Complex Fires that burned over 1 million acres and destroyed 1,767 structures.

Each of these fires ranked within the top five largest fires in state history.

Dry lightning and dry thunderstorms can be some of the most dangerous weather events during fire season, according to CAL FIRE.

According to the United States Forest Service (USFS), dry lightning is cloud-to-ground lightning without an accompanied rainfall nearby.

USFS attributes three criteria to dry lighting:

  • Rainfall less than 0.10 inches
  • Fuel
  • A positive or negative cloud-to-ground lightning strike

“If it has been hot and dry for a long period, rainfall amounts need to be larger in order to moisten the fuel bed and lessen the chances of lightning fire ignition,” the National Weather Service said. “If the surface fuel bed lies below a closed forest canopy, more rainfall is required to penetrate the canopy and reach the surface fuel.”

The National Oceanic and Atmospheric Administration (NOAA) Storm Prediction Center issues forecasts for dry lighting due to the weather event’s likelihood of starting forest fires.

In the case of the August Complex fire, 37 separate fires caused by a dry lightning storm in Tehama and Glen counties merged to become the largest wildfire in California history and burned for two months.