Inside the Race to Predict California's Next Wildfire Season

When Dr. Craig Clements ventures into the Santa Cruz Mountains twice a month with his team from San Jose State University, he’s not just checking on the shrubs. He’s reading the future of California’s fire season, one plant sample at a time.

The work sounds straightforward but carries real weight: researchers clip fresh growth from chamise shrubs, bag them in cans, return to the lab, and measure exactly how much water is sitting inside. They dry the samples in an oven, weigh them again, and the difference between wet and dry tells a powerful story about flammability. When fuels are extremely dry, risk spikes. When they’re moist, the landscape becomes harder to ignite. Dr. Clements, a professor of meteorology and director of the university’s Wildfire Interdisciplinary Research Center, leads one of dozens of teams across California doing this painstaking work year-round to track live fuel moisture in real time.

Why does this matter? California’s wildfire danger doesn’t just depend on how much vegetation is out there—it depends on how thirsty that vegetation has become. For chamise specifically, 70% fuel moisture is the critical threshold; drop to 60%, and you’ve entered very critical territory. In some Northern California regions, researchers have measured chamise as low as the 50s. Those aren’t abstract numbers—they’re early warnings that conditions are primed for disaster.

This year, Clements is particularly focused on the Sierra’s middle elevations. The region saw dramatically reduced snowpack and early snowmelt, which means less soil moisture and vegetation that will dry out sooner than usual. That spells trouble heading into late summer and fall, when offshore winds and heat waves typically accelerate fire danger. Yet Clements remains cautious about predictions. As he points out, it’s day-to-day weather—heat waves, wind events, lightning, human activity—that ultimately determines whether dry fuels become raging fires. We won’t know what August brings until a few weeks before it arrives.

The long-term trend, though, is unmistakable and sobering. We’re getting drier by the decade, Clements warns. Climate change is warming the atmosphere, which increases its demand for moisture from plants, and the Sierra’s vegetation is responding. Some plants may soon struggle to survive in areas where they’ve historically thrived. The solution Clements advocates for is clear: prescribed fire across the state to reduce fuel loads before nature—or human carelessness—ignites them. It’s not a glamorous approach, and it requires serious coordination and resources. But it’s the most direct path to genuinely lowering risk, rather than just measuring it.