CLEARLAKE, Calif. — Two thousand homes lost and two-thirds of the land burned: The residents of Lake County, a sparsely populated area north of Napa Valley, understand better than most the devastating cost of wildfires in recent years.

Yet few people in Lake County, or in many other fire-prone parts of California, could have anticipated the millions they are now spending this summer on wildfires, even before the first big one ignites.

Insurance rates have soared in some of the riskiest places, and some insurers are refusing to renew policies. Lake County politicians are fretting over the more than $700,000 the county is spending to install backup power generators for the courthouse, sheriff’s department and other government buildings. The generators are necessary because the power company has announced that this year it will turn off the power when fire risk is high.

“It’s a lot of money for us, but I really feel we don’t have a choice,” said Dennis Darling, who owns a supermarket in the town of Clearlake and is paying $100,000 to install a generator. “Every year we have these hellacious fires.”