A significant pattern shift has resulted in cooler temperatures across the eastern half of the country, with temperatures expected to continue to remain below average for the first weekend of May. The coldest stretch of the period is expected to occur Friday night through Sunday, when temperatures could drop into the low to mid-30s and fall into the mid-50s, allowing for patchy frost. A brief pattern shift is expected early next week, but temperatures are expected to return closer to average for Monday and Tuesday.