...RED FLAG WARNING IN EFFECT THROUGH 3 PM FRIDAY FOR MANY INTERIOR PORTIONS OF SOUTHWEST CALIFORNIA DUE TO EXTREME HEAT AND INSTABILITY ALONG WITH LOCALLY GUSTY WINDS AND LOW HUMIDITIES...

.A very hot and unstable air mass combined with locally gusty winds and low humidities will bring a significant risk of large plume dominated fires with rapid spread and extreme fire behavior.

* TEMPERATURES...Highs 96 to 106 across the lower elevations. Highs 85 to 95 common across the higher mountains. Lows in the mid 70s to mid 80s common in the mountains and foothills.

* INSTABILITY...Very deep mixing heights of 12,000 to 18,000 feet today through Thursday, slightly lower on Friday.

* WINDS...Southwest 10 to 20 mph with gusts 20 to 30 mph each afternoon into early evening.

* RELATIVE HUMIDITY...Minimum humidities 10 to 20 percent each day, Poor recoveries overnight hours in the mountains and foothills with humidities in the 15 to 30 percent range.

* IMPACTS...There is a significant risk of large plume dominated fires with rapid fire spread and extreme fire behavior. There is a history of large plume dominated fires this time of year with similar weather and fuel conditions, including the Bridge, Bobcat, and Station fires.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions will occur shortly. Use extreme caution with anything that can spark a wildfire. Residents near wildland interfaces should be prepared to evacuate if a wildfire breaks out. See readyforwildfire.org and wildfirerisk.org for information. close

* WHAT...Hot daytime conditions with high temperatures between 100 and 110 common. Warm overnight conditions will bring less relief than usual.

* WHERE...Most mountains and valleys of Los Angeles, Ventura, and Santa Barbara Counties.

* WHEN...Until 8 PM PDT Friday.

* IMPACTS...There is a high risk for dangerous heat illness, especially for sensitive groups like the very young, the very old, those without air conditioning, and those active outdoors.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Do not leave young children and pets in unattended vehicles. Limit strenuous activities to early morning or evening hours. Take action when you see symptoms of heat exhaustion. close

* WHAT...The South Coast AQMD has issued an air quality alert due to harmful levels of ozone pollution. Visit https://www.aqmd.gov/alertinfo to check current and forecasted air quality levels.

* WHERE...in the the South Coast Air Basin and Coachella Valley. Levels of ozone pollution can vary by time and location depending on emissions and air pollution transport.

* WHEN...from 1 PM Monday to 8 PM Friday. The highest ozone levels typically occur in the afternoon and early-evening hours.

* IMPACTS... Ozone air pollution can cause serious health problems, including trouble breathing, asthma attacks, and lung damage. Everyone can be affected, but sensitive groups such as people with lung disease, older adults, people who are pregnant, children, and those who spend a lot of time outdoors are at greater risk.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To protect your health, check air quality levels and act as needed:

* When Air Quality Index (AQI) levels are "Unhealthy for Sensitive Groups" (orange), sensitive groups as specified above should limit extended or intense outdoor activity. * When AQI is "Unhealthy" (red), everyone may experience health impacts. Sensitive groups should avoid extended time outdoors. * When AQI is "Very Unhealthy" (purple), sensitive groups should avoid all outdoor physical activity. Everyone else should avoid extended or intense outdoor activity. * When AQI is "Hazardous" (maroon), everyone should avoid all outdoor physical activity.

* ADDITIONAL DETAILS...

To help keep indoor air clean when air quality is poor:

* Keep windows and doors closed * Run your air conditioner and/or an air purifier * Do not use whole house fans or swamp coolers that bring in outside air if you have other methods to stay cool * Avoid other sources of pollution such as fireplaces, candles, incense, and grilling

To help minimize outdoor ozone air pollution levels:

* Limit the use of gasoline powered lawn and garden equipment until evening hours * Try to delay trips to the gas station and the use of household chemicals until the evening close

* WHAT...The South Coast AQMD has issued an air quality alert due to harmful levels of ozone pollution. Visit https://www.aqmd.gov/alertinfo to check current and forecasted air quality levels.

* WHERE...in the the South Coast Air Basin and Coachella Valley. Levels of ozone pollution can vary by time and location depending on emissions and air pollution transport.

* WHEN...from 1 PM Monday to 8 PM Friday. The highest ozone levels typically occur in the afternoon and early-evening hours.

* IMPACTS... Ozone air pollution can cause serious health problems, including trouble breathing, asthma attacks, and lung damage. Everyone can be affected, but sensitive groups such as people with lung disease, older adults, people who are pregnant, children, and those who spend a lot of time outdoors are at greater risk.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

To protect your health, check air quality levels and act as needed:

* When Air Quality Index (AQI) levels are "Unhealthy for Sensitive Groups" (orange), sensitive groups as specified above should limit extended or intense outdoor activity. * When AQI is "Unhealthy" (red), everyone may experience health impacts. Sensitive groups should avoid extended time outdoors. * When AQI is "Very Unhealthy" (purple), sensitive groups should avoid all outdoor physical activity. Everyone else should avoid extended or intense outdoor activity. * When AQI is "Hazardous" (maroon), everyone should avoid all outdoor physical activity.

* ADDITIONAL DETAILS...

To help keep indoor air clean when air quality is poor:

* Keep windows and doors closed * Run your air conditioner and/or an air purifier * Do not use whole house fans or swamp coolers that bring in outside air if you have other methods to stay cool * Avoid other sources of pollution such as fireplaces, candles, incense, and grilling

To help minimize outdoor ozone air pollution levels:

* Limit the use of gasoline powered lawn and garden equipment until evening hours * Try to delay trips to the gas station and the use of household chemicals until the evening close