By CBS3 Staff

PHILADELPHIA (CBS) — The Philadelphia region is kicking off the work week with hot, steamy temperatures. The heatwave across the Delaware Valley will continue through most of the day Monday.

By this afternoon it’ll be day 5 of temperatures in the 90s.

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The stretch of 90 degree days is likely to persist until Thursday. If we do break into the 90s each day, it’ll be the longest stretch of 90 degree days since August of 2017.

The high heat in addition to high humidity will prompt a Heat Advisory starting at noon across Philadelphia and its surrounding suburbs until 6 pm tonight.

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During hot and muggy conditions, it’s best to drink plenty of water, stay in an air conditioned room and if you can, stay out of the sun until the threat is over

The morning starts off dry but heavy storms are likely later in the afternoon and through the overnight hours.

Thunderstorm activity is possible across the region and storm activity will likely persist well into the nighttime hours.

It is expected to be a steamy Monday with heat index values in the upper 90s to 100s.

The heat and humidity will provide ample fuel for thunderstorms which will be rapidly developing once any storm fires off.

Storms will likely contain frequent lightning and several could turn strong to severe.

Some storms may also be slow-moving, combined with heavy rainfall potential, could yield localized flooding.

The pattern of highs in the 90s with excessive humidity and some level of storm chance will persist through Thursday.

We’ll keep a close eye on a system that will likely develop to our south.

The system may bring us some tropical moisture and thus an enhanced rain and downpour chance for Friday and Saturday.