Every year as the cool spring days get warmer and warmer, I am often asked two questions. "Will it be hot this summer" and "will it be dry this summer"? My answers are almost always the same. "Yes... it's always a hot summer" and "yes... we live in a desert... it never rains in the summer".
So let's look at the actual numbers. Boise's hottest days average 91 for the high temperature during the first 6 days of August. Despite the longest day being the first day of summer in the third week of June, the hottest temperatures lag behind the seasons because it takes time for the sun to warm the air. This is the same reason that the highest temperature of the day is in the late afternoon and not when the sun is overhead at noon.
Over the past 67 years Boise on average has seen 5.6 days with the mercury topping 100. However since the turn of the century we have seen an average of 14 days at 100+ with 2003 recording a record 20 days.
So if you think 100 degree days are not normal... think again. Our hottest days are likely right around the corner and 100 degree heat is almost ineveitable. It's been since 1982 that Boise did not see temps topping the century mark..... Keep cool !