By Geoff Bansen

PHILADELPHIA (CBS) — After an absolutely gorgeous weekend for the Delaware Valley, the heat and humidity return this week.

Monday will feature a mix of sun and clouds and highs approaching the 90 degree mark, with higher humidity as we wrap up the month of June. Most places will likely hit that mark on Tuesday and be will into the 90s by Wednesday. Remember, a heat wave is classified by three straight 90 degree days, so depending on the amount of cloud cover we see on Thursday, we could very well have our first heat wave of the 2014 season.

WATCH: Justin’s Monday Forecast

Showers and thunderstorms are likely late Wednesday and into Thursday. After all of the lovely holiday and weekend weather we’ve been experiencing so far this summer, we might be seeing a bit of a hiccup to start your holiday weekend. Tropical moisture will move up the coast later this week and could but a damper on any BBQ, beach, or firework plans. Keep in mind, this could change over the next couple of days, but the fact that the models are in fairly good agreement this early doesn’t bode well. Just keep this in mind and be prepared to postpone or make alternate plans; and definitely be sure to check back with Eyewitness Weather throughout the week!

On the flip side, any rain should clear out early Saturday morning, and the rest of the day and Sunday look great.

Today In Weather History:
1892 — An F1 tornado moved along the Delaware River shoreline at Camden, NJ, killing 2 people.
1918 — A trace of snow fell in June at Mount Pocono, Monroe Co, the first ever in June in the Mt. Holly area of responsibility, tying the Jun PA state maximum snowfall record set in 1907 and 1902.
1938 — The month ended with 10.06″ of precipitation, the wettest June in PHL records.
1949 — 11 years later, the month ended with 0.11″ of precipitation, the DRIEST June in PHL records.
1972 — The entire state of PA was declared a disaster area as a result of the catastrophic flooding caused by Hurricane Agnes (Jun 22), which claimed 48 lives, and caused $2.1 billion of damage.

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