Red flag warning issued during heat wave

A red flag warning was issued meaning fire danger is extremely high.

A red flag warning was issued meaning fire danger is extremely high.

SAN DIEGO — High temperatures combined with gusty wind and low humidity are expected to heighten the risk of wildfires in some mountain and desert areas of San Diego County again Tuesday.

A National Weather Service heat advisory for the deserts will expire at 6 p.m., but a red flag warning for the mountains and deserts is set to remain in effect until 9 p.m. Wednesday.

“A red flag warning means that critical fire weather conditions are either occurring now, or will shortly,” according to the weather service. “A combination of strong winds, low relative humidity and warm temperatures will contribute to extreme fire behavior.”

On Monday, the heat wave pushed afternoon temperatures into the 80s and 90s along the coast, the 90s to 105 in inland areas, the low to mid-90s in the East County highlands and up to 113 in the local deserts, according to the NWS. It also led to a heat record in Alpine, where the high of 102 degrees surpassed the prior Aug. 15 milestone of 101, set last year. El Cajon’s maximum mark of 103 matched its previous record for the date, also logged in 2015.

High temperatures Tuesday will be 77 to 82 degrees along the coast, 87 to 92 degrees inland, 91 to 96 degrees in the western valleys, 96 to 101 degrees near the foothills, 93 to 99 degrees in the mountains and 109 to 114 degrees in the deserts. Winds of 25 to 30 miles per hour, with gusts of up to 40 mph are possible Tuesday in the deserts and mountains.

“A low pressure trough moving into California from the northwest will strengthen the onshore flow, generating gusty southwest winds along the mountain ridges and onto the desert slopes,” according to the weather service. “The gusty winds coupled with very low relative humidity will create periods of critical wildfire conditions through Wednesday evening.”

Forecasters said any fires that develop amid red flag conditions would likely spread rapidly. Outdoor burning was discouraged.

Residents were also advised to guard against potentially serious heat- related ailments, stay hydrated, avoid unnecessary outdoor labor and check on neighbors and relatives, especially the elderly. Authorities also warned against leaving people or pets in parked cars, which can quickly become death traps in high heat.