Sometimes the jet stream (river of air circling the globe around 15 - 35,000 feet high) does nice and pleasant to us, sometimes it helps bring severe weather, and sometimes it brings a heat wave. We're getting the latter this Memorial Day weekend.
The jet stream divides the warm air from the cold, and is the storm highway. Well, take a look at the position of the jet stream this weekend. It's well to the north. Warm air resides south of the jet, and cooler air north. If we were on the northern half of the jet with it oriented from northwest to southeast, we would be enjoying cool and mainly dry weather. However, with it's position well north, and a large area of high pressure at the surface and aloft, temperatures will simply build each day heading through the weekend. The air above us will be slowly sinking, and keeping us hot and dry.
With this jet steam pattern locked in place, the map below shows all of the Southeast will be enjoying highs in the low-mid 90s! Hello Summer!!