Wildfires Stay Lit Longer as Nights Heat Up

The length of time fires burn in North America has stretched into the night, a trend linked to human‑driven climate change. Researchers found that conditions suitable for fire now last 36 % longer than they did half a century ago, and the number of days with fire‑prone weather has risen by 44 %.

In places like California, the extra hours add about 550 daily burning opportunities compared to the mid‑1970s. Southwest New Mexico and central Arizona see even larger gains, with up to 2,000 more hours each year when the weather favors fire.

These extended periods mean that fires no longer die out as temperatures drop after sunset. Instead, they can keep burning through the night and start stronger in the morning, making suppression more difficult. Recent blaze events—such as those in Los Angeles and Hawaii—demonstrated this pattern, with fires igniting after midnight.

The culprit is a warmer, drier night air that holds less moisture and can pull more water out of vegetation. Scientists note that nighttime temperatures have risen faster than daytime highs, partly because greenhouse gases trap heat and clouds act like a blanket after dark. Since 1975, the lowest nighttime temperatures in the U.S. have climbed by about 2.6 °F (1.4 °C).

This persistent heat keeps fuels—dead leaves, branches, and grasses—from rehydrating. As a result, the forest ecosystem remains in a constant state of readiness for fire, adding to the overall fuel load.

Firefighters report that battling a blaze at night is riskier and harder: wildlife may flee, and crews must contend with reduced visibility. A study of nearly 9,000 large fires from 2017‑2023 used satellite data to track hourly weather conditions and found a clear link between the new fire‑hazard climate and nighttime activity.

The trend is already visible in recent years: from 2016‑2025, U.S. wildfires averaged an area the size of Massachusetts each year—more than double the 1980s average. Canada’s burn area over the past decade is similarly higher, indicating a continent‑wide shift toward more fire‑prone conditions.

The findings serve as a stark reminder that climate change is reshaping wildfire dynamics, extending both the duration and frequency of dangerous fire events across North America.