NOAA’s National Weather Service issues a marine forecast for every coastal zone in the United States, four times daily. For Pacific Northwest cruisers, the relevant products are PZZ150-series for Puget Sound and the Strait of Juan de Fuca, PZZ100-series for the Washington and Oregon coastal waters, and PZZ200-series for the offshore waters out to 60 nm. Each is a separate forecast for a separate water body. The forecast is free, broadcast continuously on VHF weather channels (WX-1 through WX-5), and available online at weather.gov/marine.
This is the working version of how to read one — a tight blog companion to the deeper Reading Marine Weather Forecasts piece in the education library.
The anatomy of a forecast
A typical zone forecast looks like this:
NORTHERN INLAND WATERS INCLUDING THE SAN JUAN ISLANDS — Tonight: South winds 10 to 15 knots with gusts to 20 knots becoming variable 5 knots after midnight. Seas 1 to 2 ft. Patchy fog after midnight. Sunday: Northwest winds 5 to 10 knots becoming west 10 to 15 knots in the afternoon. Seas 1 to 2 ft.
Each piece has a meaning. None of it is generic.
Wind direction is where the wind is coming from. South winds blow from the south toward the north. In Puget Sound, a south wind funnels up the Sound and builds as it travels northward — useful to know if you are running south to north and counting on a quartering breeze.
Wind speed in knots. One knot = 1.15 mph. The thresholds matter: under 15 knots, comfortable cruising; 15–25, active sailing with reefs; 25–35, small craft advisory range, experienced crews only; over 35, gale, recreational boats stay in.
Gusts are the peak — typically 30–40% above sustained. Plan to the gust, not the average. “15 knots gusting 25” and “15 knots sustained, no gusts” are different sea states.
Seas are wave height in feet, trough to crest. The number alone is insufficient — period (the time between wave crests) determines whether the same height rolls under you comfortably or breaks. The forecast gives height; the zone discussion below gives period.
Visibility matters most for any passage near commercial traffic. Under 1 nm: proceed with extreme caution and sound fog signals. Under 0.5 nm: don’t go.
What most boaters miss
Two parts of the forecast that most recreational boaters skip are the most useful ones.
The synopsis. Above the per-zone forecast, NOAA includes a synopsis — a paragraph from the issuing meteorologist explaining why the forecast is what it is. “Surface high pressure over the eastern Pacific will continue to support a weak onshore flow through Sunday before a cold front approaches the Washington coast Monday afternoon.” That sentence tells you the trajectory: the calm continues another 36 hours, the front arrives Monday. The per-zone forecast is the snapshot; the synopsis is the trajectory.
The zone discussion. Some zones include a forecast discussion below — plain language explaining the meteorologist’s confidence and the alternative scenarios. This is where you find “models disagree on the timing of the trough; the forecast leans toward the GFS solution but ECMWF brings the front through six hours earlier” — useful if you are deciding whether to leave at 1100 or 1700.
Read both. They are the difference between “the wind will be 15 knots” and “the wind will be 15 knots from the south, building Monday afternoon as a cold front pushes through, with the possibility of an earlier arrival if the European model is correct.”
Where the forecast is reliable, and where it is not
NOAA’s marine forecasts are accurate within roughly 24 hours about 80% of the time. They degrade past 48 hours — by 72 hours, the forecast is a starting hypothesis, not a plan.
PNW gap winds (Strait of Juan de Fuca outflow, Chehalis Gap drainage, Hood Canal williwaws) and Puget Sound convergence-zone effects are particularly hard to model. The synoptic-scale forecast can be exactly right and your specific anchorage can be wildly different because of local topography. When the forecast says “south winds 10 knots” and your anemometer at the dock reads 25 knots northeast, trust the anemometer.
What to do with the information
The disciplined pre-departure process:
- The night before — read the synopsis and the next 48 hours. Identify any incoming systems.
- The morning of — read the freshest forecast. Note any changes from last night.
- Before casting off — check observed conditions at NOAA buoys near your route. Buoy 46087 (Neah Bay), 46211 (Grays Harbor), 46029 (Columbia River Bar) are the relevant outer-coast stations. Live wind, wave height, barometric pressure.
- Underway — keep the relevant WX channel audible at the helm. Conditions change. The forecast is a prediction, not a contract.
The cardinal rule, in three words: if uncertain, wait. Forecasts get better every six hours. There is no PNW cruise that cannot be delayed a day.
When to call the meteorologist
For passages that depend on tight forecast windows — a Strait of Juan de Fuca crossing in shoulder season, a Columbia River Bar transit, an offshore run from Astoria to San Francisco — calling the issuing forecast office for a marine briefing is allowed, encouraged, and free. The Seattle Weather Forecast Office number is (206) 526-6087. The Astoria/Portland office is (503) 261-9246. Phone in business hours; ask for the marine forecaster on duty; explain the planned passage and ask for their interpretation. They will tell you what the forecast actually means in practice.
This is one of the better-kept secrets of PNW cruising.
For the deeper version of all this — wind scales, sea-state interpretation, fog patterns, advisory thresholds, the PNW seasonal patterns (Juneuary, summer fog, autumn storm track, williwaws) — see Reading Marine Weather Forecasts in the education library.
The forecast is what the atmosphere is probably going to do. The buoy is what the water is currently doing. The window outside the boat is what is happening now. All three matter.