Tides Today & Tomorrow in Roche Harbor, San Juan Island, WA

TIDE TIMES for Tuesday, July 21, 2026
The tide is currently falling in Roche Harbor, San Juan Island, WA.
Next low tide : in 1h 00m at 4:34 pm (4.5 ft)
Next high tide : 10:51 pm (7.5 ft)
Sunset today : 9:04 pm
Sunrise tomorrow : 5:33 am
Moon phase : First Quarter (53% illuminated)
Tide Station Location : Station #9449834
Common Questions About Tides

Roche Harbor, San Juan Island, WA Tides - Sep 1989

DateHigh TideLow TideSunMoonDate
AMftPMftAMftPMftRiseSet
1Fri5:526.36:527.312:083.612:041.36:307:54New Moon1Fri
2Sat6:426.27:067.212:422.912:382.16:317:52Waxing Crescent2Sat
3Sun7:336.17:247.11:162.21:143.16:337:50Waxing Crescent3Sun
4Mon8:286.07:467.01:531.61:514.06:347:48Waxing Crescent4Mon
5Tue9:315.98:106.82:311.12:325.06:357:46Waxing Crescent5Tue
6Wed10:555.98:356.63:120.83:195.86:377:44First Quarter6Wed
7Thu12:596.13:590.64:276.46:387:42First Quarter7Thu
8Fri2:366.54:530.56:206.86:407:40First Quarter8Fri
9Sat3:286.85:560.48:536.86:417:38First Quarter9Sat
10Sun4:017.07:020.29:036.66:427:36Waxing Gibbous10Sun
11Mon12:006.24:267.28:02-0.19:206.16:447:33Waxing Gibbous11Mon
12Tue1:196.34:477.38:54-0.49:475.46:457:31Waxing Gibbous12Tue
13Wed2:326.55:067.49:40-0.410:204.46:477:29Waxing Gibbous13Wed
14Thu3:416.85:257.510:22-0.110:573.26:487:27Full Moon14Thu
15Fri4:476.95:477.611:030.611:371.86:497:25Full Moon15Fri
16Sat5:527.06:117.811:441.66:517:23Full Moon16Sat
17Sun6:577.16:387.812:210.512:272.86:527:21Waning Gibbous17Sun
18Mon8:047.07:077.81:07-0.51:124.06:547:19Waning Gibbous18Mon
19Tue9:177.07:387.61:55-1.22:035.26:557:17Waning Gibbous19Tue
20Wed10:417.08:147.32:47-1.53:036.16:567:14Third Quarter20Wed
21Thu12:137.13:44-1.34:266.76:587:12Third Quarter21Thu
22Fri1:357.34:47-0.96:376.76:597:10Third Quarter22Fri
23Sat2:377.45:57-0.48:466.27:017:08Third Quarter23Sat
24Sun3:257.57:100.19:335.57:027:06Waning Crescent24Sun
25Mon12:565.74:027.68:150.510:034.87:037:04Waning Crescent25Mon
26Tue2:275.84:337.59:080.910:264.17:057:02Waning Crescent26Tue
27Wed3:406.04:567.49:521.410:473.37:067:00Waning Crescent27Wed
28Thu4:396.25:137.210:292.011:102.57:086:58New Moon28Thu
29Fri5:306.45:257.111:042.711:361.77:096:55New Moon29Fri
30Sat6:186.65:377.111:393.57:116:53New Moon30Sat
DateHigh TideLow TideSunMoonDate
AMftPMftAMftPMftRiseSet
Tidal Data Source: (9449834)

Common Questions About Roche Harbor, San Juan Island, WA Tides

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What time does the tide turn (slack tide) in Roche Harbor, San Juan Island, WA today?

Slack tide in Roche Harbor, San Juan Island, WA is approximately 7:42 pm — midway between the next high and low tide, when tidal current is weakest. This is the preferred window for boat crossings, underwater visibility, and fishing in areas with strong currents.

Is this week a spring tide or neap tide in Roche Harbor, San Juan Island, WA?

Roche Harbor, San Juan Island, WA is currently in a neap phase. Tonight's moon is 53% illuminated. Spring tides (largest swings) occur near new and full moons; neap tides (smallest swings) occur near first and third quarter moons. Tidal ranges this week are near their weekly minimum.

What datum are Roche Harbor, San Juan Island, WA tide heights measured from?

Tide heights on this page are measured from Mean Lower Low Water (MLLW), the U.S. NOAA standard. A height of 0 ft represents the 19-year average of each day's lower low tide. Negative values indicate a "minus tide" — water levels below that long-term reference.

What factors can affect the tide predictions for Roche Harbor, San Juan Island, WA?

Tide predictions for Roche Harbor, San Juan Island, WA come from NOAA's harmonic analysis and are typically accurate within about ±10 minutes on timing and ±0.5 ft on height. Actual water levels can deviate further due to sustained winds, atmospheric pressure changes, river flow, and storm surge. During major weather events, be sure to check US Harbors weather pages for factors that could impact tidal predictions.

Which NOAA station provides tide data for Roche Harbor, San Juan Island, WA?

Tide data for Roche Harbor, San Juan Island, WA is sourced from NOAA Station #9449834. View the official NOAA station page at https://tidesandcurrents.noaa.gov/stationhome.html?id=9449834.

What is the moon phase in Roche Harbor, San Juan Island, WA tonight?

Tonight the moon over Roche Harbor, San Juan Island, WA is First Quarter (53% illuminated). This places Roche Harbor, San Juan Island, WA in a neap tide cycle, so tidal ranges are near their weekly minimum this week.

US Harbors Tidal Data

The data in our tide charts, tide tables, and tide graphs is provided by NOAA and others. These predictions are derived mathematically from numerous inputs, including data from historical tide stations and nearby locations where sensors are actively recording. As shown in the tide graph at the top of this page, “Predicted” tides (blue) are what forecasting models expect to happen. “Observed” tides (red) are those recorded by local sensors in real time, overlaid on the predictions for direct comparison. We display Observed water levels for a select group of harbors including Portland, Maine, where a physical sensor monitors water levels in real time.

LEARN MORE ABOUT OUR TIDE DATA