Over the next few days, excessive heat will once again plague cities like San Francisco, Portland, and Seattle. The high temperature will be around 90 degrees. Even with the windows open, the heat inside the vehicle can reach temperatures 10 to 20 degrees higher than the outside air temperature. Portland has only seen three consecutive days of triple-digit temperatures seven times in the last 77 years - the most recent coming in August 1981. The hottest temperature ever recorded in Seattle was set July 29, 2009, when the mercury reached 103 degrees.
Seattle, which has experienced only three 100 degree days in 123 years, is also seemingly unprepared for the heatwave about to hit the region.
The National Weather Service office in Seattle said that temperatures in the region will "probably be within 5 degrees of the all-time records".
"Overall, expect humid and hot conditions to continue through much of the week", the weather service said. In plain English, this means that this is an incredibly rare and extreme heat situation. But if you're hoping for the off-chance the predictions will be wrong, bad news: It's about certain the high won't dip below 100.
The all-time record high recorded in Portland is 107 degrees.
The low on Tuesday was 59, 2 degrees below normal and 12 degrees above the record low of 47 for the date, set in 1976.
The heat is the result of an unusually intense high pressure system aloft, sometimes referred to as a heat dome. When nighttime temperatures remain high, it's even more hard for the body to cool off, increasing the risk of heat-related illness.