Atmospheric Sciences professor Cliff Mass reports that “[t]he western United States is experiencing one of the coldest end-of-winter periods in the historical record…,” with areas in the region having experienced high temperatures in recent weeks more than 15℉ below the normal average high temperatures for the time period. (see the figure below)
For instance, the average temperature for Los Angeles for the last week in February and the first week in March was the coldest for that stretch of time since official record keeping began in the 1930s. Similarly, San Francisco has experienced its coolest maximum temperatures since the 1960s, and for Portland the last two weeks were tied for the second coldest for that time period since record keeping began.
In fact, dozens of cities in the western and northwestern United States set monthly low temperature records in recent weeks, including cities in Arizona, California, Idaho, Montana, Nevada, Oregon, and Washington State. See the figure below: