Heat, humidity in local forecast

For those who feel this summer has been exceptionally unbearable, it is only going to get worse.

Temperatures above 100 degrees this week will be made more uncomfortable as monsoonal moisture moves over the Sierra Nevada mountains and even over the San Joaquin Valley later this week.

And, it is not just the Valley that will be affected. On Monday, the National Weather Service issued an excessive heat warning for valley, mountain and desert areas around greater Los Angeles, as well as along the Central Coast.

Temperatures could reach 109 degrees in the Antelope Valley and 88 in Cambria.

The highs in Porterville are predicted to be 103 today, 102 on Wednesday and 103 on Thursday.

The catch is the humidity and possibly a shower or two. If the clouds are thick enough, temperatures will be slightly less than predicted, but not much, said National Weather Service meteorologist Jeff Barlow.

“We’ll see some relative humidity,” he said, adding that will make the nights much warmer. The weather service is calling for a low temperature tonight of 77 degrees, — 6 degrees warmer than Monday night. Those uncomfortable conditions are expected to last into Friday.

Monday was the 32nd day since June 14 the mercury has reached or topped 100 degrees and Barlow said the long-range forecasts show triple-digits to continue for the next 7-10 days.

“We’re in the dog days of summer,” he said when the average temperature is the highest of the entire year at 99 degrees. That average, which has existed for about a month now, finally drops to 98 degrees on Aug. 7.

Barlow said the clouds will be up high (10,000 feet) and any rainfall will likely dissipate before reaching the Valley floor. However, he did not rule out a shower here and there on Wednesday and again on Thursday. The big concern is lightning. “We are very concerned about the potential for fire starts,” he said, but added that right now it looks like the lightning will be “isolated and scattered.” However, without rain, any strike could spark a fire in the foothills.

The heat wave is also enveloping much of Northern California, where areas north of San Francisco will see temperatures in the 90s and even topping 100.