As triple-digit heat continues to be forecast for the central San Joaquin Valley, fires in nearby counties produced smoke Sunday that helped make skies gray, the National Weather Service in Hanford said.
The overcast was caused by two factors. First was drifting smoke. Winds from the southeast pushed smoke from the Schaeffer Fire in Tulare County toward Fresno County. Also contributing were the Alamo Fire in San Luis Obispo County and Whitter Fire in Santa Barbara County.
An air quality alert was issued for those most sensitive to pollution. William Peterson, meteorologist engineer at the National Weather Service office in Hanford, said poor air quality will effect those who are sensitive to pollution in Fresno, Kern, Kings, Madera and Tulare counties, along with Sequoia National Park.
A second reason for the grayish skies was the monsoonal flow of air that is characteristic of July. Humid air flowing north from Mexico brought clouds and the threat of thunderstorms, mainly over the Sierra.
An excessive heat warning was in place for most of the Valley, but as of midafternoon Fresno had not yet gone over 100 degrees for the day. Sunday was forecast to be 107 degrees in Fresno.
The current heat wave that began July 3 shows no sign of letting up. Triple digits are forecast all week and into the weekend.
Peterson recommends that on hot days people try to avoid outdoor activities, stay hydrated and seek out cooling shelters if needed.