In anticipation of the hottest weekend the region has seen in a while, weather experts are warning some Washingtonians to be wary of “critical” fire conditions that will hit parts of the state’s southwest interior particularly hard.

National Weather Service Seattle sent out a “red flag” warning Friday afternoon for communities just west of the Cascade Mountains — extending from the top of the state into the southern end of the Olympic Peninsula, said meteorologist Maddie Kristell. The warning has been issued from 11 a.m. Saturday to 11 p.m. Sunday.

A couple of factors, including low humidity and unstable air conditions, contributed to concerns about fire safety, Kristell said.

“Another thing (meteorologists) considered was that because we’ve had kind of a longer period of warmer temperatures and not too much meaningful precipitation, we also have to consider how dry the fields are out there,” she said. “Anything else that’s been drying would be easily combustible and easier to catch a spark.”

She recommended people stay hydrated, look for shady spots when possible, limit exposure to the sun and be mindful of sources of ignition.

Though the Seattle area and other communities surrounding the Puget Sound aren’t at as high a risk of seeing fires, Kristell said it’s important to remain vigilant about heat and fire safety.

Sunday is expected to see the worst of the heat, with temperatures in the low- to mid-90s near Seattle and in the upper 90s further inland.