For Olympia Airport, (1941-2015), I have compiled the number of “hot” days (>= 89 F) per decade. The threshold temperature for a hot day was set to make an annual mean frequency of about 7 days per year.
1940s* 68 days
1950s 69
1960s 76
1970s 76
1980s 81
1990s 78
2000s 70
2010s* 77
* Normalized to 10 years
There was a slight uptick going from the 1950s into the 1960s, but there has been little change over the past 6 decades (since the 1960s) in the number of “hot” days per year.
Years with greatest number of “hot” days at Olympia Airport:
1) 1967 20 days
2) 1958 19
3) 2015 18
4) 1981 17
5) 1985 15
5) 1992 15
5) 2009 15
Years with least number of “hot” days at Olympia Airport:
1) 2011 0 days
1) 1976 0
1) 1964 0
1) 1954 0
2) 1983 1
2) 1966 1
2) 1957 1
The Climate of Oregon and Washington 