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The Rum Creek fire burns vigorously after sunset near Merlin, Oregon on August 28, 2022. Credit: Robert Hiatt, NOAA National Weather Service
This graph shows how the frequency of nights with dry fuels predisposed to burning has increased between the 1981-2000 period and the 2011-2020 period. This has created the conditions for increased fire activity at night, a time when firefighters could once count on falling temperatures and rising humidity to give them a break. Credit: Pacific Marine Environmental Laboratory.
For decades, firefighting crews counted on falling temperatures and rising humidity at night to dampen wildfire activity, allowing them to rest, regroup and prepare for the next day.
Over the last 20 years though, satellite measurements have confirmed a change reported in the western US by firefighters on the ground: a dramatic increase in nighttime fire activity by larger fires. Previous studies attributed the increase to warmer, drier nights, conditions that help to maintain the flammability of fuels.
New research from NOAA, the University of Washington and the U.S. Forest Service has investigated other weather conditions that influence fire behavior, the extent to which these factors have been changing over recent decades and how they may have contributed to changes in nighttime fire behavior.
"We looked for simultaneous changes in winds, atmospheric mixing and fuel moisture that might enhance nocturnal fire activity," said lead author Andy Chiodi, a University of Washington scientist working with NOAA’s Pacific Marine Environmental Laboratory. "Our... more
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