The Sierra region will likely experience significant increases in extremely hot days, with a five to 10-fold jump iby late century. The region’s current 30-year average for days over 95°F is roughly eight days per year, but this will likely increase to 13 to 19 days per year on average over the next 25 years, 21 to 33 days by mid-century, and 37 to 84 days–or nearly three full months–of extremely hot days by the end of this century. The tail risks are more significant: there is a 1-in-20 chance of more than 22 days per year of extremely hot days in the near term, 41 days by mid-century, and 103 days over 95°F each year by century’s end.