The Philadelphia region is now in its fourth heat wave of the summer.

After highs of 90 degrees Saturday and 91 Sunday, the region got back into heat-wave territory with a 93-degree day Monday.

On top of that, climbing dew points are making it feel more humid than over the weekend — but not as bad as last week, when heat indexes passed the 100-degree mark for several days.

The heat wave is expected to continue Tuesday, with a projected high of 94, and could break on Wednesday, when a cold front is likely to trigger thunderstorms and heavy rain.

There’s a chance of thunderstorms for Thursday and Friday, with highs in the upper 80s.

Previous heat waves this summer were June 26 to 29, July 2 to 6, and July 19 to 22, when heat indexes soared above 100 degrees.

Meanwhile, a code orange air quality alert was issued Monday, meaning air pollution concentrations were potentially unhealthy for children, the elderly, and people suffering from asthma, heart disease or other lung ailments. More-moderate ozone levels are forecast for Tuesday, according to AirNow.gov.

The National Weather Service warned Monday of a moderate risk of rip currents in the ocean at the New Jersey Shore and Delaware beaches, saying those conditions were expected to continue Tuesday.