MARINE REPORT / 72 HOURS

Tumon Bay Snorkel Report Today

Guam · Updated Sun 21:29 (ChST) · Source: Snapshot

The skinny

Marginal Data updated Sun 21:29 (ChST)

Tumon Bay looks marginal today. The least-bad daylight window is around Mon 17:00, but waves is limiting the forecast.

Right now (forecast)

Poor · 0.0/10

Mon 00:00 (ChST)

Later today

Poor · 2.7/10

Mon 17:00 (ChST)

Next three days

Fair · 4.1/10

Wed 16:00 (ChST)

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

Score: 2.7/10

Best time: Mon 17:00

Main risk: Waves

Best morning signal: Mon 10:00 (Poor).

Best afternoon signal: Mon 17:00 (Poor). Peak afternoon wind is about 9.2 m/s.

Email me when it is good

Sunrise

06:11

Sunset

18:00

Water

27.2°C

Max air

28.9°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

Monday

❌ Poor conditions

Main blocker: Waves

Tuesday

⚠️ Fair conditions

Main blocker: Waves

Wednesday

⚠️ Fair conditions

Main blocker: Waves

Best available hours

  • Wed 16:00: Fair (0.41) · still limited by waves, tide/current
  • Tue 14:00: Fair (0.40) · still limited by waves, tide/current
  • Wed 17:00: Fair (0.38) · still limited by waves, tide/current

Why this verdict

Main blockers across the next 72 hours:

  • Waves (68 hours)
  • Tide/current (68 hours)
  • Darkness (44 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, Wed 16:00

Nearby alternatives in Guam

No nearby alternatives available.

Advanced forecast data

Viewing historical data

Mon 00:00 – Thu 00:00 (ChST)

Previous day Yesterday Next day Live

Snorkel Score (selected 24h)

Best snorkel score is 0.43 around Mon 15:00; 4 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 1.04m to 1.14m).

Wind is at or below 5.4m/s in 24/24 sampled hours (range 0.64 to 4.67m/s).

Tides range from 0.26m to 0.84m; 2 of 24 hours are in or near peak slack windows.

72-hour historical overview
Poor ❌ Limited
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Fair ⚠️ Fair
Poor ❌ Limited
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Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Poor ❌ Limited
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Fair ⚠️ Fair
Fair ⚠️ Fair
Poor ❌ Limited
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Fair ⚠️ Fair
Fair ⚠️ Fair
Poor ❌ Limited
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Fair ⚠️ Fair
Poor ❌ Limited
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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
Mon 00:00 1.14 · high 1.25 · good 29.60 · good Poor
Mon 01:00 1.14 · high 0.92 · good 29.60 · good Poor
Mon 02:00 1.14 · high 0.64 · good 29.60 · good Poor
Mon 03:00 1.12 · high 0.87 · good 29.60 · good Poor
Mon 04:00 1.12 · high 1.21 · good 29.60 · good Poor
Mon 05:00 1.12 · high 0.90 · good 29.60 · good Poor
Mon 06:00 1.10 · high 1.06 · good 29.60 · good Poor
Mon 07:00 1.10 · high 1.55 · good 29.60 · good Poor
Mon 08:00 1.10 · high 1.72 · good 29.60 · good Poor
Mon 09:00 1.08 · high 2.64 · good 29.60 · good Poor
Mon 10:00 1.08 · high 3.35 · good 29.60 · good Fair
Mon 11:00 1.08 · high 4.35 · good 29.70 · good Poor
Mon 12:00 1.06 · high 4.44 · good 29.70 · good Poor
Mon 13:00 1.06 · high 4.22 · good 29.80 · good Fair
Mon 14:00 1.06 · high 3.69 · good 29.80 · good Fair
Mon 15:00 1.04 · high 3.72 · good 29.90 · good Fair
Mon 16:00 1.04 · high 4.67 · good 29.90 · good Poor
Mon 17:00 1.04 · high 4.57 · good 29.90 · good Poor
Mon 18:00 1.04 · high 4.08 · good 29.80 · good Poor
Mon 19:00 1.04 · high 3.58 · good 29.70 · good Poor
Mon 20:00 1.04 · high 3.01 · good 29.70 · good Poor
Mon 21:00 1.04 · high 3.46 · good 29.70 · good Poor
Mon 22:00 1.04 · high 3.98 · good 29.70 · good Poor
Mon 23:00 1.04 · high 2.26 · good 29.60 · good Poor
Tue 00:00 1.04 · high 3.20 · good 29.60 · good Poor
Tue 01:00 1.14 · high 3.12 · good 29.60 · good Poor
Tue 02:00 1.14 · high 2.67 · good 29.60 · good Poor
Tue 03:00 1.14 · high 2.95 · good 29.60 · good Poor
Tue 04:00 1.14 · high 4.92 · good 29.60 · good Poor
Tue 05:00 1.14 · high 1.94 · good 29.60 · good Poor
Tue 06:00 1.12 · high 2.37 · good 29.60 · good Poor
Tue 07:00 1.12 · high 3.64 · good 29.60 · good Poor
Tue 08:00 1.12 · high 4.46 · good 29.60 · good Poor
Tue 09:00 1.10 · high 4.44 · good 29.60 · good Poor
Tue 10:00 1.10 · high 5.35 · good 29.60 · good Poor
Tue 11:00 1.10 · high 5.24 · good 29.60 · good Poor
Tue 12:00 1.10 · high 5.46 · high 29.70 · good Poor
Tue 13:00 1.10 · high 5.47 · high 29.70 · good Poor
Tue 14:00 1.10 · high 5.32 · good 29.70 · good Poor
Tue 15:00 1.08 · high 4.37 · good 29.70 · good Poor
Tue 16:00 1.08 · high 3.85 · good 29.70 · good Poor
Tue 17:00 1.08 · high 4.97 · good 29.70 · good Poor
Tue 18:00 1.06 · high 4.42 · good 29.70 · good Poor
Tue 19:00 1.06 · high 3.99 · good 29.70 · good Poor
Tue 20:00 1.06 · high 4.08 · good 29.60 · good Poor
Tue 21:00 1.04 · high 3.59 · good 29.60 · good Poor
Tue 22:00 1.02 · high 3.49 · good 29.50 · good Poor
Tue 23:00 1.02 · high 4.46 · good 29.50 · good Poor
Wed 00:00 1.00 · high 3.75 · good 29.40 · good Poor
Wed 01:00 1.00 · high 3.31 · good 29.40 · good Poor
Wed 02:00 1.06 · high 1.77 · good 29.40 · good Poor
Wed 03:00 1.08 · high 2.51 · good 29.40 · good Poor
Wed 04:00 1.08 · high 2.75 · good 29.40 · good Poor
Wed 05:00 1.08 · high 2.25 · good 29.40 · good Poor
Wed 06:00 1.10 · high 1.91 · good 29.40 · good Poor
Wed 07:00 1.10 · high 2.88 · good 29.40 · good Poor
Wed 08:00 1.10 · high 3.49 · good 29.50 · good Poor
Wed 09:00 1.12 · high 3.41 · good 29.50 · good Poor
Wed 10:00 1.12 · high 3.46 · good 29.50 · good Fair
Wed 11:00 1.12 · high 3.31 · good 29.60 · good Fair
Wed 12:00 1.12 · high 3.30 · good 29.70 · good Poor
Wed 13:00 1.12 · high 3.38 · good 29.80 · good Poor
Wed 14:00 1.12 · high 2.53 · good 29.90 · good Fair
Wed 15:00 1.10 · high 1.28 · good 30.00 · good Fair
Wed 16:00 1.10 · high 4.28 · good 30.10 · good Poor
Wed 17:00 1.08 · high 4.30 · good 30.10 · good Poor
Wed 18:00 1.08 · high 2.49 · good 30.00 · good Fair
Wed 19:00 1.06 · high 2.49 · good 29.90 · good Poor
Wed 20:00 1.06 · high 2.47 · good 29.80 · good Poor
Wed 21:00 1.10 · high 2.73 · good 29.70 · good Poor
Wed 22:00 1.08 · high 2.82 · good 29.70 · good Poor
Wed 23:00 1.06 · high 2.33 · good 29.60 · good Poor