Today will be about as hot and humid as it’s possible to get here in Maine and New Hampshire, at least in southern parts of the area. A warm front will be lifting north through our region today and will be responsible for the heat and humidity as well as some afternoon shower/storm activity.
The first round of showers associated with the warm front is drifting southeast towards Sebago Lake as I write this around 6:15 AM. These will generally tend to weaken as they drift towards Portland later this morning. I think we’ll see a bit of a lull in shower activity during the mid/late morning hours before storms begin popping up early this afternoon.
These storms will initially develop in the mountains around noon-1 PM before moving east-southeast towards the coastline. The combination of hot temperatures, high humidity, and some cooler mid-level air will support plenty of instability to fuel the storms. Gusty winds, heavy rain, and frequent lightning will be the main threats with these storms but any time we get a warm front setup like this, we can’t totally rule out a tornado or two. The best chance, as always, is in the Sebago Lake region.
High temps today will range from the upper 70s/low 80s in the far northern mountains to the mid/upper 90s in southern NH. Most of central/southern NH and coastal/foothills regions in Maine will see temps above 90 this afternoon. Dew points near or above 70 will send heat index values into the triple digits over southern NH and adjacent parts of SW ME. Use appropriate caution if you need to be outside this afternoon.