MARINE REPORT / 72 HOURS

Tumon Bay Snorkel Report Today

Guam · Updated Sun 12:07 (ChST) · Source: Snapshot

The skinny

Marginal Data updated Sun 12:07 (ChST)

Tumon Bay looks marginal today. The least-bad daylight window is around Sun 18:00, but waves is limiting the forecast.

Right now (forecast)

Poor · 1.7/10

Sun 14:00 (ChST)

Later today

Poor · 1.7/10

Sun 15:00 (ChST)

Next three days

Fair · 3.8/10

Tue 14:00 (ChST)

Model estimates using Open-Meteo; not observations or safety guarantees. Check official advisories and conditions at the beach.

Score: 1.7/10

Best time: Sun 18:00

Main risk: Waves

No useful morning window is showing yet.

Best afternoon signal: Sun 15:00 (Poor). Peak afternoon wind is about 13.6 m/s.

Email me when it is good

Sunrise

06:11

Sunset

18:00

Water

27.8°C

Max air

26.5°C

Sky

Cloudy

100% cloud

No good model window in the next 72 hours

Use the best-available section for the least-bad times.

3-day planner Best available Show data

3-day planner

Sunday

❌ Poor conditions

Main blocker: Waves

Monday

❌ Poor conditions

Main blocker: Waves

Tuesday

⚠️ Fair conditions

Main blocker: Waves

Best available hours

  • Tue 14:00: Fair (0.38) · still limited by waves, tide/current
  • Tue 17:00: Fair (0.38) · still limited by waves, tide/current
  • Tue 16:00: Poor (0.35) · still limited by waves, tide/current

Why this verdict

Main blockers across the next 72 hours:

  • Waves (69 hours)
  • Tide/current (69 hours)
  • Darkness (47 hours)

Jellyfish drift risk

Drift estimate from wind, swell, current and warm water.

Low · 34/100

Low drift risk now.

warm water supports seasonal jellyfish activity; surface drift/current is noticeable; local shoreline exposure is not mapped yet.

Sightings override the model: if you see small purple jellyfish with long trailing tentacles, treat them as sting-capable and give them space.

Upcoming high tides

Tue 16:00

Nearby alternatives in Guam

No nearby alternatives available.

Advanced forecast data

Viewing historical data

Wed 14:00 – Sat 14:00 (ChST)

Previous day Yesterday Next day Live

Snorkel Score (selected 24h)

Best snorkel score is 0.33 around Wed 17:00; 0 of 24 hours are good, fair, or excellent.

Score trend, higher is better. Excellent ≥ 0.72, good 0.55–0.72, fair 0.35–0.55.

Conditions (24h trends)

Tap a chart to load just that series.

0/24 sampled hours stay at or below 0.36m (range 0.74m to 0.98m).

Wind is at or below 5.4m/s in 19/24 sampled hours (range 2.74 to 5.85m/s).

Tides range from 0.13m to 0.92m; 1 of 24 hours are in or near peak slack windows.

72-hour historical overview
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Scoring methodology (for technical users)

We score each hour from 0 to 1 using daylight and these weighted components:

  • Wave height (35%): best below 0.36m, then decreases as it rises.
  • Wind speed (25%): best below 5.4m/s, lower is better.
  • Sea surface temperature (15%): best within 20.6°C to 30.4°C.
  • Tide and currents (15%): best around slack/high-tide windows.
  • Daylight (10%): visibility is better in daylight, so night hours score lower.
Detailed hourly data table
Time Wave (m) Wind (m/s) Sea temp (°C) Status
Wed 14:00 0.74 · high 5.75 · high 30.30 · good Poor
Wed 15:00 0.76 · high 5.85 · high 30.40 · good Poor
Wed 16:00 0.78 · high 4.75 · good 30.40 · good Poor
Wed 17:00 0.78 · high 4.40 · good 30.40 · good Poor
Wed 18:00 0.78 · high 3.95 · good 30.30 · good Poor
Wed 19:00 0.78 · high 3.40 · good 30.30 · good Poor
Wed 20:00 0.78 · high 3.32 · good 30.20 · good Poor
Wed 21:00 0.82 · high 3.77 · good 30.10 · good Poor
Wed 22:00 0.82 · high 3.28 · good 30.10 · good Poor
Wed 23:00 0.82 · high 2.93 · good 30.10 · good Poor
Thu 00:00 0.84 · high 3.28 · good 30.00 · good Poor
Thu 01:00 0.88 · high 4.13 · good 30.00 · good Poor
Thu 02:00 0.88 · high 3.03 · good 30.00 · good Poor
Thu 03:00 0.90 · high 2.74 · good 30.00 · good Poor
Thu 04:00 0.90 · high 3.23 · good 30.00 · good Poor
Thu 05:00 0.90 · high 3.04 · good 30.00 · good Poor
Thu 06:00 0.92 · high 2.84 · good 30.00 · good Poor
Thu 07:00 0.92 · high 3.50 · good 30.00 · good Poor
Thu 08:00 0.94 · high 3.78 · good 30.00 · good Poor
Thu 09:00 0.94 · high 4.57 · good 30.00 · good Poor
Thu 10:00 0.96 · high 5.25 · good 30.00 · good Poor
Thu 11:00 0.96 · high 5.66 · high 30.00 · good Poor
Thu 12:00 0.98 · high 5.80 · high 30.10 · good Poor
Thu 13:00 0.98 · high 5.80 · high 30.10 · good Poor
Thu 14:00 1.00 · high 6.45 · high 30.10 · good Poor
Thu 15:00 1.02 · high 5.50 · high 30.10 · good Poor
Thu 16:00 1.04 · high 5.90 · high 30.10 · good Poor
Thu 17:00 1.04 · high 6.15 · high 30.10 · good Poor
Thu 18:00 1.06 · high 4.45 · good 30.10 · good Poor
Thu 19:00 1.06 · high 3.99 · good 30.10 · good Poor
Thu 20:00 1.08 · high 4.20 · good 30.10 · good Poor
Thu 21:00 0.96 · high 4.57 · good 30.00 · good Poor
Thu 22:00 0.96 · high 4.88 · good 30.00 · good Poor
Thu 23:00 0.96 · high 5.01 · good 30.00 · good Poor
Fri 00:00 0.98 · high 4.83 · good 30.00 · good Poor
Fri 01:00 0.98 · high 5.19 · good 30.00 · good Poor
Fri 02:00 0.94 · high 4.29 · good 30.00 · good Poor
Fri 03:00 0.94 · high 4.92 · good 30.00 · good Poor
Fri 04:00 0.94 · high 3.95 · good 30.00 · good Poor
Fri 05:00 0.96 · high 4.57 · good 30.00 · good Poor
Fri 06:00 0.96 · high 4.83 · good 30.00 · good Poor
Fri 07:00 0.98 · high 4.01 · good 30.00 · good Poor
Fri 08:00 1.00 · high 4.06 · good 30.00 · good Poor
Fri 09:00 1.00 · high 5.17 · good 30.00 · good Poor
Fri 10:00 1.02 · high 7.55 · high 30.00 · good Poor
Fri 11:00 1.04 · high 7.05 · high 30.00 · good Poor
Fri 12:00 1.04 · high 7.16 · high 30.00 · good Poor
Fri 13:00 1.06 · high 7.95 · high 30.00 · good Poor
Fri 14:00 1.08 · high 7.85 · high 30.00 · good Poor
Fri 15:00 1.12 · high 7.77 · high 30.00 · good Poor
Fri 16:00 1.14 · high 7.68 · high 30.00 · good Poor
Fri 17:00 1.14 · high 7.54 · high 30.00 · good Poor
Fri 18:00 1.14 · high 6.66 · high 30.00 · good Poor
Fri 19:00 1.14 · high 5.68 · high 30.00 · good Poor
Fri 20:00 1.14 · high 5.87 · high 29.90 · good Poor
Fri 21:00 1.28 · high 5.89 · high 30.00 · good Poor
Fri 22:00 1.30 · high 7.71 · high 30.00 · good Poor
Fri 23:00 1.32 · high 7.45 · high 30.00 · good Poor
Sat 00:00 1.34 · high 6.68 · high 30.00 · good Poor
Sat 01:00 1.36 · high 8.05 · high 29.90 · good Poor
Sat 02:00 1.38 · high 7.50 · high 29.90 · good Poor
Sat 03:00 1.40 · high 7.86 · high 29.90 · good Poor
Sat 04:00 2.64 · high 10.43 · high 29.90 · good Poor
Sat 05:00 2.66 · high 10.59 · high 29.90 · good Poor
Sat 06:00 2.70 · high 10.46 · high 29.90 · good Poor
Sat 07:00 2.72 · high 10.48 · high 29.90 · good Poor
Sat 08:00 2.76 · high 11.39 · high 29.90 · good Poor
Sat 09:00 2.80 · high 10.95 · high 29.90 · good Poor
Sat 10:00 2.84 · high 11.40 · high 29.90 · good Poor
Sat 11:00 2.86 · high 11.58 · high 29.90 · good Poor
Sat 12:00 2.90 · high 12.73 · high 29.90 · good Poor
Sat 13:00 2.92 · high 12.56 · high 30.00 · good Poor