Valley residents are getting hit by the one-two punch of higher temperatures and higher humidity levels this week, with triple-digit temperatures through at least Thursday.

Unlike our usual catchphrase when faced with Central California’s furnace-like summer temperatures, this week we won’t be able to say that “at least it’s a dry heat.”

A combination of factors — the return of a high-pressure dome moving westward from Texas, a high-pressure system easing its way south from the Pacific Northwest, and the residual snowpack in the Sierra from the winter’s record snows — are bringing higher-than-normal temperatures and moisture levels to the Valley and Coast Range this week, National Weather Service meteorologist Jerald Meadows said Monday.

The National Weather Service has declared a heat advisory through Thursday, with Valley temperatures ranging from 100 to 107 degrees.

Fresno’s high is forecast to peak at 105 on Wednesday and then drop below the triple digits starting Friday, which means this weekend will be better than recent ones to get out and do some yard work or other outside activities, Meadows said.

Thunderstorms are forecast this week to pop up over the Sierra, and there could be some shower activity in the Valley, Meadows said.

More Humid

The increase in humidity comes from moisture in the snowpack that is being pushed west by the high-pressure ridge into the Valley, he said. More moisture comes from a tropical system developing in the eastern Pacific south of Baja California.

And humidity is the big reason why overnight temperatures this week will remain in the mid to upper 70s in Fresno.

This summer tropical weather has moved further north in California this year because of warmer waters in the Pacific, Meadows said.

The long-term forecast is for warmer-than-normal temperatures through the end of the month and possibly into the early portion of the fall, he said. The wild card is whether tropical systems could develop and lower temperatures, Meadows said.

How to Stay Cool

During a heat advisory, the National Weather Service provides the following advice:

• Stay in air-conditioned spaces.
• Drink plenty of water.
• Reduce time in the sun.
• Limit outdoor activities.