The California Valley experienced a significant increase in temperatures, with temperatures remaining 10 to 15 degrees above average and expected to remain warm throughout the week. High temperatures in the low 90's are typical for June, not March, according to the weather service. High pressure over California has weakened a bit, allowing temperatures to remain above the average for the next few days. The past week, particularly in March, has seen temperatures reach 90 degrees 4 times, pushing past 91 degrees 3 times and setting 5 daily warmest overnight low temperature records. The heat is causing the Sierra snowpack to melt rapidly, leading to early closure of ski resorts in the Sierra Nevada earlier than usual. The earliest opening date for the Tioga Road through Yosemite is April 8, and it is uncertain when it will reopen.