It's a return to summer-like conditions. Highs should stay in the 80 degree range for several more days.
Before I get into the forecast, let me bring you up to speed on August's weather...
Only two of the first 17 days of August have had temperatures above normal. Saturday, the 17th, was the first day with a high over 80 degrees (It was 81). The coolest day was the 13th with a high of only 57. Sunday should be a degree or two warmer than that.
As for rain, we've only had 0.57" of rain in Negaunee Township. That's more than an inch below normal. Our last rainfall was a small amount spread out between the 11th and 13th. Conditions are pretty dry currently. The week ahead should bring in some new rain and humidity.
Look for mostly sunny skies on Sunday. Highs will mainly be in the low 80s, but will most likely remain in the upper 70s near the lakes, especially Lake Michigan with a southwest wind. That southwest wind comes from behind a high pressure system that is the dominating weather factor for the eastern half of the U.S. As it slowly moves away east, we'll have that south wind last for a while.
That means Sunday night's lows will be mild in the 60s for most of the U.P. Overnight, clouds will move in from the west trapping in even more heat for the western counties where lows may only drop into the upper 60s. With those clouds comes an increasing chance for rain or thundershowers, but Sunday night's rain potential is very low and will be confined to the west.
On Monday, there is a greater chance for thunderstorms. Skies should generally be partly cloudy, but a small area of low pressure will likely spawn a few light rain showers. Given the warm temperatures, some of those showers may turn into isolated and brief thunderstorms. Highs will be mainly in the low to mid 80s.
Monday night will be another nice evening with lows only falling into the 60s. Skies will become mostly clear and rain potential diminishes as it cools down.
Tuesday's weather will be similar to Monday's, but warmer. That means greater chances for thunderstorms in the heat of the afternoon, but again, anything that develops will likely be isolated and brief. Highs will likely climb well into the 80s for the whole U.P.
Wednesday will probably be the warmest day of the week with highs approaching 90 ahead of a cold front. Wednesday is also the day most likely to see scattered thunderstorms across Upper Michigan.
Temperatures will cool down starting Thursday. More storms are possible towards next weekend.