Smoke from Fourth of July fireworks left parts of Southern California under poor air quality conditions Sunday morning, and the smoky air could linger into the afternoon, forecasters say.

KTLA’s Kirk Hawkins said an air quality alert was in effect through about 10:45 a.m. Sunday but was expected to be extended until at least 3 p.m. as lingering smoke continued to affect the region.

Air quality monitors Sunday morning showed unhealthy conditions in several communities, including Altadena, El Monte, Jurupa Valley, Rancho Cucamonga, Redlands and Hesperia.

People with asthma or other respiratory conditions should use caution and limit prolonged outdoor activity while air quality remains poor, Hawkins said. Children, older adults and pets may also be more vulnerable to the smoky conditions.

Despite the hazy air inland, low clouds along the coast were beginning to clear Sunday morning, making way for another pleasant day near the beaches. Temperatures were in the upper 60s early Sunday, including 67 degrees in Santa Monica and 68 degrees in Fullerton, according to Hawkins.

While the smoky skies are expected to improve, a warming trend is on the way for much of Southern California.

High temperatures in the Los Angeles Basin are forecast to reach about 84 degrees Sunday before climbing into the mid-80s by Wednesday and Thursday, Hawkins said.

The Inland Empire is expected to warm from about 92 degrees Sunday into the triple digits by the middle of the week, where heat advisories could become necessary.

The San Fernando Valley is also expected to heat up significantly, with highs forecast to reach 94 degrees Monday, 97 degrees Tuesday and 100 degrees Wednesday before easing back into the upper 90s Thursday and the low 90s by Friday, according to Hawkins’ seven-day forecast.

Breezy afternoon and evening winds are also expected to continue across the mountains and deserts, with gusts of 30 to 40 mph possible.

Hawkins said a strengthening ridge of high pressure over the Four Corners region will be responsible for the warming trend while also pulling in some subtropical moisture, creating occasionally muggy conditions and even the possibility of isolated sprinkles in some areas.

As temperatures climb later this week, residents are encouraged to stay hydrated, avoid strenuous outdoor activity during the hottest part of the day, never leave children or pets in parked vehicles and check on older adults and others who may be more vulnerable to the heat.

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