First Alert: Extreme heat continues, plus an early look at Friday's Celtics parade forecast

It’s not the heat, it’s the overnight low temperatures.

Studies show that the lack of cooling at night is a major factor in heat-related stress. With our morning temps in record WARM territory Wednesday and Thursday morning, this is a gentle reminder to take it easy in the coming days. Heat illnesses (dizziness, fatigue, weak, rapid pulse) can come on quickly in this heat, so proceed with caution and stay hydrated!

The heat will tighten its grip through Wednesday and Thursday, with Thursday bringing the warmest conditions. Highs are near 95 degrees in Boston on Wednesday. Temperatures haven’t been this hot since August of 2022.

As school starts to end, many routines are different and shifting. This should serve as a reminder to check the back seat for pets and children. It’s worth putting a purse, brief case or cell phone in the back seat to create a forced habit to check, before you lock the car.

Outdoor activities should be paused during the heat of the day, between 1-5 p.m. – as heat index values touch or tip 100 degrees.

There’s some temporary relief in the form of thunderstorms in the afternoon. They’ll be scant Wednesday – limited to towns in southern New Hampshire. Severe weather isn't likely Wednesday - mostly spotty showers at times through the Merrimack Valley between 6-10 p.m.

A severe thunderstorm was issued at 11:35 a.m. through 12:15 p.m. for parts of northwestern Vermont. See all severe weather alerts here.

Thursday brings another chance for rain in the afternoon, with storms possible from 3-10 p.m. The severe storms will again, favor the Monadnock Region and Northern Worcester County around 5 p.m., with rain tapering after 9 p.m. Boston will encounter storms and downpours around 5 p.m. This, along with the East wind, will bring the dangerous heat to a conclusion. As highs on Friday are in the lower 80s.

While some rain lingers early Friday morning, the day tends to be dry for starters. The Celtics’ parade may be timed perfectly to avoid the showers. There could be a leftover shower very early Friday, then storms may fire later in the afternoon to the west of Boston. Central Mass and Western Mass will see higher rain chances through the midday and afternoon, but at The Garden, rain chances look lower until the afternoon to evening.

Cooler air will infiltrate too as the winds shift to the northeast after a cold frontal passage. This will mark the end of the heat wave and some of that cooler air will spill into the weekend.

Saturday seems pleasant with highs near 80, but Sunday could feature more heat and humidity with a chance for some afternoon thunderstorms.

Be safe and keep your cool.