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In Washington, Lake Merwin is a reservoir used for time on and around the water. It covers roughly 4,000 surface acres (about 6 square miles). If you are planning a trip, Swofford Pond are also nearby. The page brings together an hourly and 7-day forecast, wind and gust outlook, and activity scores for boating, paddling, and swimming. Current weather, wind, and activity conditions for Lake Merwin are updated throughout the day.
Updated
No active alerts for this lake as of the last check (Oct 9, 12:20 AM PDT). Alerts are re-checked automatically; see the official source for updates.
Overall Good (87/100) across 4 activities. Best right now: Boating (99/100).
How the score is calculated →Best excellent fishing window, averaging 92/100 across these hours. Wind 6 mph from the west-northwest. Dusk hours (18:00 local). Derived from the hourly forecast; official alerts are not forecast and are checked separately.
| Metric | 7a | 8a | 9a | 10a | 11a | 12p | 1p | 2p | 3p | 4p | 5p | 6p | 7p | 8p | 9p | 10p | 11p | 12a | 1a | 2a | 3a | 4a | 5a | 6a |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Temp (°F) | 55° | 54° | 54° | 53° | 52° | 52° | 52° | 51° | 52° | 52° | 54° | 56° | 56° | 56° | 58° | 58° | 58° | 57° | 55° | 53° | 50° | 48° | 48° | 47° |
| Wind (kts) | 0 | 0 | 1 | 1 | 0 | 0 | 0 | 1 | 2 | 3 | 4 | 4 | 5 | 5 | 6 | 6 | 6 | 6 | 5 | 3 | 1 | 0 | 0 | 0 |
| Direction | — | — | NW | NW | — | — | — | SW | SW | SW | W | W | NW | NW | NW | NW | NW | NW | NW | NW | NW | — | — | — |
| Gusts (kts) | 3 | 3 | 6 | 5 | 3 | 2 | 2 | 3 | 5 | 7 | 9 | 9 | 10 | 11 | 13 | 14 | 15 | 16 | 13 | 11 | 7 | 4 | 1 | — |
| Precip % | 0% | 0% | 0% | 0% | 0% | 6% | 12% | 19% | 60% | 83% | 76% | 56% | 33% | 10% | 2% | 2% | 0% | 0% | 0% | 1% | 0% | 0% | 2% | 4% |
| Time | Temp | Wind | Gusts | Precip | Cloud | Condition |
|---|---|---|---|---|---|---|
| Fri, 12 AM PDT | 55°F | Calm | 4 mph | 0% | 43% | Partly Cloudy |
| Fri, 1 AM PDT | 54°F | Calm | 4 mph | 0% | 48% | Patchy Fog |
| Fri, 2 AM PDT | 54°F | 1 mph NW (315°) | 7 mph | 0% | 55% | Patchy Fog |
| Fri, 3 AM PDT | 53°F | 1 mph WNW (293°) | 6 mph | 0% | 64% | Patchy Fog |
| Fri, 4 AM PDT | 52°F | Calm | 4 mph | 0% | 59% | Patchy Fog |
| Fri, 5 AM PDT | 52°F | Calm | 2 mph | 6% | 77% | Mostly Cloudy |
| Fri, 6 AM PDT | 52°F | Calm | 2 mph | 12% | 85% | Patchy Fog |
| Fri, 7 AM PDT | 51°F | 1 mph SW (225°) | 4 mph | 19% | 89% | Patchy Fog |
| Fri, 8 AM PDT | 52°F | 2 mph SW (225°) | 6 mph | 60% | 92% | Light Rain Likely |
| Fri, 9 AM PDT | 52°F | 3 mph SSW (203°) | 8 mph | 83% | 91% | Light Rain |
| Fri, 10 AM PDT | 54°F | 5 mph WSW (248°) | 10 mph | 76% | 88% | Light Rain |
| Fri, 11 AM PDT | 56°F | 5 mph W (270°) | 10 mph | 56% | 90% | Light Rain Likely |
| Fri, 12 PM PDT | 56°F | 6 mph WNW (293°) | 12 mph | 33% | 86% | Chance Light Rain |
| Fri, 1 PM PDT | 56°F | 6 mph WNW (293°) | 13 mph | 10% | 73% | Mostly Cloudy |
| Fri, 2 PM PDT | 58°F | 7 mph WNW (293°) | 15 mph | 2% | 78% | Mostly Cloudy |
| Fri, 3 PM PDT | 58°F | 7 mph WNW (293°) | 16 mph | 2% | 59% | Partly Sunny |
| Fri, 4 PM PDT | 58°F | 7 mph WNW (293°) | 17 mph | 0% | 47% | Mostly Sunny |
| Fri, 5 PM PDT | 57°F | 7 mph WNW (293°) | 18 mph | 0% | 38% | Mostly Sunny |
| Fri, 6 PM PDT | 55°F | 6 mph WNW (293°) | 15 mph | 0% | 44% | Partly Cloudy |
| Fri, 7 PM PDT | 53°F | 3 mph WNW (293°) | 13 mph | 1% | 30% | Partly Cloudy |
| Fri, 8 PM PDT | 50°F | 1 mph WNW (293°) | 8 mph | 0% | 34% | Partly Cloudy |
| Fri, 9 PM PDT | 48°F | Calm | 5 mph | 0% | 41% | Partly Cloudy |
| Fri, 10 PM PDT | 48°F | Calm | 1 mph | 2% | 46% | Partly Cloudy |
| Fri, 11 PM PDT | 47°F | Calm | 0 mph | 4% | 55% | Mostly Cloudy |
| Sat, 12 AM PDT | 47°F | Calm | 0 mph | 3% | 52% | Mostly Cloudy |
Official National Weather Service hourly forecast. Showing 10 of 25 hours. Wind arrows point the way the wind is blowing; the compass point and degrees show where it comes from.
| Period | Overnight October 9, 2026 | Friday October 9, 2026 | Friday Night October 9, 2026 | Saturday October 10, 2026 | Saturday Night October 10, 2026 | Sunday October 11, 2026 | Sunday Night October 11, 2026 | Columbus Day October 12, 2026 | Monday Night October 12, 2026 | Tuesday October 13, 2026 | Tuesday Night October 13, 2026 | Wednesday October 14, 2026 | Wednesday Night October 14, 2026 | Thursday October 15, 2026 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Temp (°F) | 50° | 59° | 42° | 57° | 39° | 63° | 39° | 65° | 42° | 60° | 47° | 62° | 45° | 69° |
| Wind | NW 1 mph | WSW 0 to 7 mph | WNW 0 to 6 mph | WSW 1 mph | N 2 mph | N 2 mph | N 2 mph | N 0 to 3 mph | N 3 mph | S 1 mph | SE 1 mph | SW 1 mph | N 3 mph | ENE 0 to 3 mph |
| Gusts | 7 mph | 18 mph | 15 mph | 5 mph | 6 mph | 7 mph | 7 mph | 7 mph | 7 mph | 5 mph | 5 mph | 5 mph | 5 mph | 5 mph |
| Precip % | 6% | 83% | 9% | 45% | 2% | 0% | 0% | 0% | 4% | 29% | 43% | 40% | 9% | 2% |
| Forecast |
No active USGS or USACE telemetry gauge is currently mapped to Lake Merwin. Not available from a verified source for this lake.
Good for fishing (84/100), from 5 available inputs. Supporting this: Wind 0 mph from the east. 0% chance of precipitation. Not available from a verified source for this lake: pressure trend, water temperature. Confidence is moderate (74%) because some inputs are unavailable or older than ideal.
Excellent for boating (99/100), from 4 available inputs. Supporting this: Wind 0 mph from the east. Gusts to 4 mph. Not available from a verified source for this lake: visibility and conditions, verified water access. Confidence is moderate (84%) because some inputs are unavailable or older than ideal.
Fair for sailing (62/100), from 4 available inputs. Supporting this: Gusts are within 4 mph of sustained wind, so the breeze is steady. No active official alerts for this lake. Working against it: Wind 0 mph is light; expect limited sailing. Not available from a verified source for this lake: visibility. Confidence is high (88%).
Excellent for kayaking (98/100), from 5 available inputs. Supporting this: Wind 0 mph from the east. Gusts to 4 mph. Confidence is high (90%).
Water temperature is not available from a verified source for this lake. No swimming score is shown without it.
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Individual boat ramp GPS coordinates are maintained under the jurisdiction of WA Parks & Wildlife Authority. Public boaters should verify seasonal launch water levels, gate hours, and daily vehicle/vessel fees before traveling.
Lake Merwin is a versatile freshwater reservoir in WA, overseen by state and local natural resource agencies to provide safe, sustainable outdoor recreation for all visitors. The lake supports active watersports, pontoon cruising, and bank fishing along accessible public easements. Checking current weather alerts and wave forecasts ensures a safe trip.
Valid freshwater sport fishing license issued by Washington Department of Fish and Wildlife (WDFW) is required for anglers age 15+. Digital license on mobile is accepted.
Mandatory Clean, Drain & Dry inspection. Out-of-area craft require on-site Aquatic Invasive Species (AIS Quagga/Zebra) inspection or decontamination before launch. USCG life jackets required for all.
Public shoreline and boating access managed by State & Local Authorities. Verify seasonal gate hours, launch fees, and parking rules before travel.
High-speed motorboating, pontoon cruising, wakeboarding, and water skiing across main channels. Target gamefish include Chinook Salmon, Coho Salmon, Rainbow Trout, Kokanee Salmon. Morning hours typically provide optimal glassy conditions for kayak and stand-up paddleboard (SUP) touring.
Warm water temperatures, peak swimming, active watersports, and open full-service campgrounds. Highest weekly attendance; plan early arrivals on summer weekends.
Spring pre-spawn and fall feeding transitions create prime trophy angling conditions. Cooler air, lower boat traffic, and vibrant seasonal shoreline foliage.
Mild year-round outdoor climate. Uncrowded waters, active winter bass and crappie fishing, and open year-round boat launch access.
No external source rows are cited by the data currently shown on this page.
Updated
Scores are heuristics, not safety guarantees. LakeRadar scores summarize available conditions and are not a substitute for official warnings, local rules, or on-water judgment.
All telemetry for Lake Merwin is synchronized directly from authorized federal and state monitoring networks (USGS, NWS, NOAA, and state environmental authorities). Observations are strictly instrumented readings — unmonitored sensors are transparently disclosed rather than synthetic estimates.
Last source audit: Oct 9, 12:20 AM PDT