EVERETT, OCT. 1: It is finally starting to feel like fall, with cool crisp morning temperatures dipping into the 40s and in some places like Arlington, dropping into the 30s.
September finished as yet another drier-than-average month. Paine Field Everett will end the month about a third of an inch below normal rainfall, the fifth month this year with below average. For the year, total rainfall is about one and three-quarters of an inch below average.
September temperatures at Everett’s Paine Field have been above normal for all nine months so far this year – quite remarkable. When averaging all the daily high and low temperatures, Paine Field is about two degrees above normal for the year. July was exceptionally warm, finishing the month at 4.9 degrees above normal.
The dry weather is expected to continue this week. A couple of weak weather systems moving from west to east into British Columbia will brush the North Sound on Tuesday and again late Friday. The primary threat of any light rainfall is close to the Canadian border, the Olympics, and the northern Cascades.
Otherwise, the region should have plenty of sunshine with seasonal fall areas of morning fog. High temperatures will primarily be in the 60s, though a few places today and again Friday, Oct. 4, could crack the 70-degree mark such as in Cascade foothills.
With the overall dry weather and cooler nights, it is the time of year for leaves on trees to turn to their vibrant fall colors. Leaves on mountain trees are turning color now and some lowland trees are also starting to turn.
Why Do Leaves Change Colors?
The change from green leaf colors is driven primarily by the shrinking hours of daylight and the growing length of nights. Depending on the variety of tree, biochemical processes in leaves end the production of green chlorophyll, unmasking two other chemicals within leaves – displaying their colors.
Weather conditions play a role in the brilliance of leaf colors, with temperature and moisture the primary influences. The amount of moisture in the soil also impacts autumn colors.
Like weather, soil moisture varies from year to year. These two highly variable factors result in no autumn season tree colors and timing being alike. A warm spring and summer, and warm sunny fall days with cool nights similar to this year’s start to fall can potentially produce the most brilliant fall colors in trees.
Looking ahead into the coming weekend and next week, the longer-range weather outlook offers above-average temperatures and relatively dry conditions. With these circumstances, the next few weeks are likely the best time to view fall tree colors along mountain highways. Trees in the North Sound lowlands should also turn to their full fall colors by mid-October as well. And Japanese Maples will reveal brilliant reds before their leaves drop.
