A heat wave is affecting regions from the Southwest to the Great Lakes, with temperatures climbing past 100 degrees Fahrenheit in many areas, prompting heat advisories for over 63 million people. Phoenix, Arizona reported one of its hottest starts to June on record. Unusual cold weather and snow are forecasted for the northern Rockies and Pacific Northwest, with heavy snow expected in areas around Glacier National Park. The central Gulf Coast is bracing for heavy rains and potential flash flooding due to a surge of tropical moisture. At the same time, recent storms have already caused significant flooding in southern Florida.