A firefighter in Idaho works after dark
Idaho Bureau of Land Management/Flickr
A firefighter in Idaho works after dark in 2008. Idaho is one of the places that the new study finds that the drying power of nighttime air has increased dramatically over the past 40 years.

Firefighters have reported that Western wildfires are starting earlier in the morning and dying down later at night, hampering their ability to recover and regroup before the next day’s flareup.

A study by University of Washington and U.S. Forest Service scientists shows why: The drying power of nighttime air over much of the Western U.S. has increased dramatically in the past 40 years. The paper was published online in July in Geophysical Research Letters, a journal of the American Geophysical Union.

“Nighttime is an important time in fire management. When fires die down at night it gives firefighters a chance to rest, move equipment and strategize. The problem firefighters are reporting is an unexpected increase in nighttime fire activity,” said lead author Andy Chiodi, a UW research scientist at the Cooperative Institute for Climate, Ocean & Ecosystem Studies, a joint center with the National Oceanic and Atmospheric Administration. “Our findings support that this has been going on over the last 40 years over much, but not all, of the Western U.S.”

Earth’s atmosphere is warming due to climate change, and warming in many places has been greater at night. Warmer night air had been suspected as the culprit altering the daily pattern of wildfire activity, with burns continuing later into the night.

Read more at UW News »