While starting on a sizzling note in Pittsburgh, the week will end with cooler air making a comeback.
Another warm and humid day will unfold on Tuesday with temperatures rising into the middle and upper 80s, falling just short of the day's record high of 90 F from 1991. Thunderstorms may develop in the afternoon and evening.
More numerous showers and thunderstorms will be around on Wednesday ahead of an approaching cold front. The combination of the storminess and clouds will hold temperatures to the upper 70s. Humidity, however, will remain high.
The week will end on a cooler note with highs in the 60s returning. The cool spell may start with soaking rain on Thursday.
A slow-moving storm system will prevent a return of the summerlike warmth through at least next weekend.
Tropical moisture may put outdoor Memorial Day plans in jeopardy from Washington D.C., to Boston on Monday.
Thunderstorms and soaking rain will threaten Memorial Day ceremonies, cookouts and vacations for millions on Monday.
Tropical Depression Two has developed northeast of the Bahamas and will approach the southeastern coast of the United States with downpours, building surf and an increasing breeze during Memorial Day weekend.
South East England will face rain threaten to ruin Monday's bank holiday, while the rest of the United Kingdom enjoys another mostly dry and mild day.
Violent storms whirled through the central United States this week, spawning large tornadoes on multiple days.
The UEFA Champions League comes to a close Saturday evening in Milan, Italy, but showers could become a hindrance to players.
Bracketville, TX (1880)
Twenty people drowned in a cloud burst -- 12.43" of rain.
Snowstorm; up to 10".
Greensboro, NC (1961)
36 degrees, latest ever in 30s.