How to get your trees ready before the November–March wind season

In Washington and Oregon, 79% of the High Wind, Strong Wind and Ice Storm reports NOAA logged from January 2016 to June 2026 began between November and March. October is the last quiet month to find the defects that turn a windy night into a tree on the roof, and to get them fixed while crews still have open calendars.

When the wind and ice actually arrive

This count covers every High Wind, Strong Wind and Ice Storm report for Washington and Oregon in NOAA’s Storm Events files from January 2016 through June 2026. Of 1,493 reports, 1,185 began in November through March. January alone had 345, December 248 and November 257, while June, July and August together had 13.

The split is sharper in Oregon, where 82% of those reports (678 of 824) fell in the five winter months, than in Washington at 76% (507 of 669). Where NOAA recorded a measured gust on a High Wind report, the median was 55 knots, about 63 mph, and the highest was 108 knots. The month-by-month tables for each state are on Oregon storm records and Washington storm records.

Rain sets up the wind. NOAA’s 1991–2020 normals put 65% of Seattle-Tacoma’s 39.34 inches of yearly precipitation and 65% of Portland airport’s 36.92 inches in November through March; Salem and Eugene are at 70%. The USDA Forest Service silvics manual records heavy Douglas fir blowdown in the Pacific Northwest after heavy rain and wind, because saturated soil lets a shallow root plate move.

Walk your trees in October

A Mississippi State University Extension risk guide, written for Mississippi but built on general tree mechanics, reports that more than 80% of trees that fail in storms had a defect beforehand. Most of those defects are visible from the ground if you look on purpose. Walk every tree that could reach your house, driveway, a bedroom or the service line, and check the items on the ISA’s homeowner list:

• Dead or broken limbs, and limbs hanging in the crown (“hangers”).
• Cracks or splits in the trunk or at a fork between two trunks.
• Mushrooms or conks at the base, or soft, punky wood.
• Soil that is cracked or heaved on one side of the trunk, or a lean that is new.
• Recent trenching, grading or a new driveway within the root zone.
• Past topping, with clusters of upright sprouts.

Our tree risk checklist walks through the same questions. A tree that is fully dead and within reach of a target is a removal, not a pruning job; see dead tree removal.

Prune for structure now, not during a storm

The fixes that matter before winter are removing dead wood and hangers, shortening a long limb over the roof with a reduction cut, and lightening the weaker stem of a split fork. The USDA’s How to Prune Trees sets the limits a good crew works within: remove no more than a quarter of the living crown at once, cut back to a side branch at least a third the diameter of the cut stem, and never top a tree.

Taking too much off a tree in a single visit can leave the crown more exposed to wind. If the crew’s plan is “thin it hard so the wind blows through”, ask how much of the live crown that removes. The options are explained on crown thinning and reduction. Dead wood can come out any time of year under the USDA guide, so it does not have to wait for dormancy.

When to get a written assessment

If a tree over the house shows a crack, a cavity, a conk or a new lean, a certified arborist with the ISA Tree Risk Assessment Qualification can rate it before the January peak. A Level 2 assessment is a 360-degree inspection with a mallet, probe and binoculars, written up with a likelihood-and-consequence rating. What it includes is on tree risk assessment.

The written report has a second use. Washington and Oregon courts tie a tree owner’s liability for a fall to whether the owner knew or should have known of a defect (Lewis v. Krussel in Washington, Taylor v. Olsen in Oregon). A dated report showing you acted is your record.

Limbs near power lines are not a homeowner job

Washington’s L&I rule (WAC 296-24-960) and Oregon OSHA’s tree-service rule (OAR 437-002-0306) keep unqualified people at least 10 feet from overhead lines up to 50 kV. The utility clears its primary lines; the service drop to your house is often your responsibility. Puget Sound Energy says it does not trim service lines, and Avista calls the service wire the homeowner’s responsibility, while both offer to disconnect it so a crew can work. Portland General Electric takes tree requests at 503-736-5460. Each utility’s rules are on utility tree trimming.

Paperwork to do before the storm

• Photograph your trees. Dated photos of each large tree show their condition before a claim.
• Read the tree section of your policy. Washington’s Insurance Commissioner says removal is usually covered only if the tree hit your home, garage or car; Oregon’s Division of Financial Regulation says the same about a tree that falls without damaging the residence.
• Check permits for any planned removal. Portland regulates private trees from 12 inches in diameter, and Seattle from 6 inches; a dead or dangerous tree usually gets the simpler path.
• Save the numbers. Your utility’s outage line, and what to do if a tree does come down, on emergency tree service.

Why the stakes are higher than a roof

NOAA’s fatality file codes 20 storm deaths in Washington and Oregon since 1996 as “Under Tree”. Fifteen happened between November and March, including two in the Portland metro winter storm of January 14, 2024 and one near Everett in the windstorm of November 19, 2024. An October walk-around is cheap compared with any of that.

Sources

1. NOAA NCEI, Storm Events bulk CSV files, details and fatalities, January 2016 to June 2026 (WA/OR extract; counts computed for this article), checked 2026-10-02.
2. NOAA NCEI, U.S. Climate Normals 1991–2020, monthly precipitation (Seattle-Tacoma, Portland, Salem, Eugene stations), checked 2026-10-02.
3. USDA Forest Service, Silvics of North America: Pseudotsuga menziesii, checked 2026-10-02.
4. Tree Health Assessment and Risk Management (P3717), Mississippi State University Extension, 2025 (general principles only), checked 2026-10-02.
5. International Society of Arboriculture, Recognizing Tree Risk (2021), checked 2026-10-02.
6. USDA Forest Service, How to Prune Trees, NA-FR-01-95 (rev. 2012), pp. 5, 9, 14–16, checked 2026-10-02.
7. ISA, Tree Risk Assessment Qualification, checked 2026-10-02.
8. Lewis v. Krussel, 101 Wn. App. 178 (2000); Taylor v. Olsen, 282 Or 343 (1978), checked 2026-10-02.
9. WAC 296-24-960, Working on or near exposed energized parts; Oregon OSHA Division 2/R, OAR 437-002-0306, checked 2026-10-02.
10. Puget Sound Energy, Tree trimming; Avista, Tree trimming; Portland General Electric, Tree maintenance, checked 2026-10-02.
11. Washington Office of the Insurance Commissioner, Winter weather and insurance coverage, checked 2026-10-02.
12. Oregon Division of Financial Regulation, Storms and your home insurance, checked 2026-10-02.
13. City of Portland, Tree removal and replanting permits (PCC 11.40); Seattle SDCI, Tree removal (SMC 25.11), checked 2026-10-02.

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