Historical weather data, all-time temperature records, and monthly climate averages for Mount Vernon, WA. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5th in Mount Vernon runs mild and often wet — expect a high near 56° and a low around 39°, with a 58% chance of rain. The date's extremes tell a wide story: 71° back in 1906 on the warm end, and a teeth-chattering 27° low as recently as 1999. Snow, at least, is essentially off the table.
Mount Vernon's all-time records reveal a town that can surprise you in any direction. The mercury once hit 99° on June 30, 1915, and plunged to -2° on January 26, 1957 — a 101-degree spread between the extremes. A single November storm in 1911 dumped 4.01 inches of rain in one day, while February 2011 buried the area under 13 inches of snow.
Summer is the clear sweet spot here, with highs peaking around 75–77° from late July through mid-August — genuinely pleasant Pacific Northwest weather. Come January, you're looking at average highs in the mid-40s and plenty of grey skies. If you're rain-averse, avoid mid-November, which is historically the wettest stretch of the year.