Another air quality alert is in effect for Philly for Sunday, and more heat is likely during the week

Another air quality alert is in effect for Philly and its neighboring Pennsylvania counties Sunday, and it looks like more heat, and that summer of 2025 favorite — smoke — are poised to return during the week.

The state Department of Environmental Protection hoisted the Code Orange air-quality advisory Saturday night, saying it expected ozone conditions to worsen Sunday afternoon.

In addition, NOAA says smoke may appear in the upper-atmosphere over parts of the region late in the day.

It could become a more-frequent visitor during the week when temperatures are due to climb, said Nick Guzzo, a National Weather Service meteorologist in the Mount Holly office.

However, he said he did not expect the smoke to mix down into lower levels of the atmosphere.

Temperatures could reach 90 or better Tuesday through Friday, peaking on Wednesday, the weather service said, although the heat will not reach the ferocity that it did the end of July and in June.

But at least on Sunday, bright sun and light winds will be favorable for cooking ground ozone — not to be confused with the benign stuff in the high atmosphere that blocks ultraviolet radiation.

Ground ozone forms when chemicals in the air react with sunlight. It occurs most frequently in summer, commonly generated by car exhaust and industrial pollutants, although smoke also can contribute to ozone production.

On Code Orange days, health officials advise people with respiratory conditions to eschew vigorous outdoor activity.

Save for the ozone, Sunday overall should be a pleasant day weather-wise with highs in the 80s on the mainland and at the Shore, where the nearly full moon will be rising into mostly clear skies.

Summer forecasts are notoriously changeable, but it does appear that the run of 90 or better may not make it into the weekend.

So far August has been quite cool with temperatures in Philadelphia averaging about 3.5 degrees below normal, quite a contrast to the steaminess of July. It also has been bone dry — with no measurable rain reported yet at Philadelphia International Airport.

Shower chances are in the outlooks Wednesday through Friday, but those may or may not happen.

One thing that will happen is that the “Dog Days” of summer will end.

Traditionally the Dog Days run from July 3 through Aug. 11. They are so-named for the appearance of Sirius, the “dog star,” which was so bright that the ancient Romans believed it contributed to summer heat.

The Romans did have some better ideas.