Severe weather is possible Tuesday and Wednesday, along with the extreme heat warning in western Pennsylvania.

As promised, the heat arrived yesterday and was every bit as bad as expected. Thankfully, the first day of the expected heat wave started on a weekend, with area pools and libraries packed. 

Today will be the day when many folks won't have any option but to go out into the heat. For those without the luxury of going to work in a well-air-conditioned work space, today through Wednesday will be tough with hot and humid conditions in place. 

Pittsburgh and all of Allegheny County are under an extreme heat warning through Wednesday evening. Westmoreland, Fayette, Washington, Beaver and Butler counties are also under the extreme heat warning.  

An extreme heat warning is issued here when heat index values are expected to be above 105 degrees. A heat advisory is issued when heat index numbers reach 100 degrees to 105 degrees.

For those who are being impacted by this weather, remember the basics of staying hydrated and trying to take it easy. More than 1000 people every year die of heat exhaustion due to extreme heat. Similar to last week's flash flooding, action by you can limit the impact of this active weather.

Looking ahead, extreme heat will be around through at least this Wednesday.  While things do improve, I have us flirting with hitting 90 degrees through next Monday. Storm chances return on Tuesday, and even though isolated, they will bring some brief relief from the heat to a couple of people. 

Afternoon storms turn scattered on Wednesday, with severe weather again being possible. Stormy afternoons will remain possible for the rest of the week in the afternoon hours.