I dug up an old post I made about the second blast in Dec 1990 (28th/29th):
Huge northerly blast. Trees and power lines down in the Seattle area from 60+ mph gusts. PDX advected into the low 20's on NW winds that reached 25 mph sustained:
PDX has yet to match the 22 degree maximum on 12-29-1990, yet at the time it was probably considered an afterthought as maximums had been 19-20-21 on the 20th-22nd.
This shot of Arctic air was actually colder than the earlier "main event" from the 19th-23rd in parts of the interior PNW. Kalispell, MT hit -35 on the 29th, tying the monthly record from 1968 and coming within 3 degrees of the all-time record (-38 on 1-30 & 1-31 in 1950). Yakima hit -16, just missing the monthly record of -17 from 12-17-1964. Also on the 29th/30th, numerous stations in NE Oregon recorded their lowest minimums of the month, beating out the earlier blast: -38 at Ukiah (tying monthly record from 1983), -33 at Enterprise 20NNE (all-time record for POR 1969-2010), -31 at Elgin (all-time record with POR back to 1937), -30 at Enterprise (tying monthly record from 1964), and -26 at Pendleton Experiment Station (tying monthly record from 1983).
In Washington state, this blast was also colder than the earlier event in many areas, especially east of the Cascades. Republic hit -27 on the 29th, the lowest temperature in the state for December 1990; Blaine hit 3 degrees and Wenatchee Experiment Station fell to -20 on the 29th as well. For the Wenatchee Exp. Station, this was an all-time record during its 47 year existence (1950-1997).
The late December 1990 freeze was one of the most damaging on record in fruit-growing areas of eastern WA, due to widespread readings in the -10's and -20's without insulation from snow cover. In the Methow Valley, this was described as the worst freeze since December 1968 in terms of damage to orchards.