MARINE REPORT / 72 HOURS

Tumon Bay Snorkel Report Today

Guam · Updated Sat 23:18 (ChST) · Source: Snapshot

The skinny

Marginal Data updated Sat 23:18 (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 · 0.0/10

Sun 01:00 (ChST)

Later today

Poor · 1.7/10

Sun 10:00 (ChST)

Next three days

Fair · 3.9/10

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

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

Best afternoon signal: Sun 12:00 (Poor). Peak afternoon wind is about 16.0 m/s.

Email me when it is good

Sunrise

06:11

Sunset

18:00

Water

29.2°C

Max air

26.9°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

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 (0.39) · still limited by waves, tide/current
  • Tue 15:00: Fair (0.37) · still limited by waves, tide/current
  • Tue 17:00: Poor (0.33) · still limited by waves, tide/current

Why this verdict

Main blockers across the next 72 hours:

  • Waves (69 hours)
  • Tide/current (69 hours)
  • Wind (53 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

Sun 01:00 – Wed 01:00 (ChST)

Previous day Yesterday Next day Live

Snorkel Score (selected 24h)

Best snorkel score is 0.38 around Sun 18:00; 1 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 1.3m to 1.54m).

Wind is at or below 5.4m/s in 11/24 sampled hours (range 1.77 to 6.9m/s).

Tides range from 0.23m to 0.83m; 2 of 24 hours are in or near peak slack windows.

72-hour historical overview
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Fair ⚠️ Fair
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
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
Sun 01:00 1.54 · high 5.78 · high 29.40 · good Poor
Sun 02:00 1.36 · high 4.72 · good 29.40 · good Poor
Sun 03:00 1.36 · high 5.93 · high 29.40 · good Poor
Sun 04:00 1.36 · high 5.42 · high 29.40 · good Poor
Sun 05:00 1.36 · high 5.88 · high 29.40 · good Poor
Sun 06:00 1.38 · high 4.60 · good 29.40 · good Poor
Sun 07:00 1.38 · high 5.17 · good 29.30 · good Poor
Sun 08:00 1.38 · high 4.87 · good 29.30 · good Poor
Sun 09:00 1.36 · high 6.31 · high 29.30 · good Poor
Sun 10:00 1.36 · high 6.77 · high 29.40 · good Poor
Sun 11:00 1.36 · high 6.90 · high 29.40 · good Poor
Sun 12:00 1.36 · high 6.39 · high 29.50 · good Poor
Sun 13:00 1.36 · high 6.34 · high 29.70 · good Poor
Sun 14:00 1.36 · high 6.29 · high 29.80 · good Poor
Sun 15:00 1.34 · high 6.42 · high 29.80 · good Poor
Sun 16:00 1.34 · high 6.08 · high 29.90 · good Poor
Sun 17:00 1.34 · high 5.52 · high 29.90 · good Poor
Sun 18:00 1.32 · high 4.36 · good 29.80 · good Fair
Sun 19:00 1.32 · high 3.82 · good 29.70 · good Poor
Sun 20:00 1.30 · high 3.30 · good 29.60 · good Poor
Sun 21:00 1.34 · high 2.74 · good 29.30 · good Poor
Sun 22:00 1.32 · high 2.21 · good 29.30 · good Poor
Sun 23:00 1.32 · high 1.95 · good 29.30 · good Poor
Mon 00:00 1.30 · high 1.77 · good 29.30 · good Poor
Mon 01:00 1.30 · high 2.37 · good 29.30 · good Poor
Mon 02:00 1.18 · high 1.36 · good 29.30 · good Poor
Mon 03:00 1.18 · high 1.48 · good 29.30 · good Poor
Mon 04:00 1.18 · high 1.43 · good 29.30 · good Poor
Mon 05:00 1.18 · high 1.61 · good 29.30 · good Poor
Mon 06:00 1.18 · high 2.01 · good 29.30 · good Poor
Mon 07:00 1.18 · high 2.75 · good 29.30 · good Poor
Mon 08:00 1.18 · high 2.79 · good 29.30 · good Poor
Mon 09:00 1.20 · high 3.08 · good 29.30 · good Poor
Mon 10:00 1.20 · high 3.51 · good 29.30 · good Poor
Mon 11:00 1.20 · high 3.55 · good 29.40 · good Poor
Mon 12:00 1.18 · high 3.65 · good 29.50 · good Poor
Mon 13:00 1.18 · high 3.58 · good 29.60 · good Poor
Mon 14:00 1.18 · high 3.47 · good 29.70 · good Fair
Mon 15:00 1.18 · high 3.37 · good 29.70 · good Fair
Mon 16:00 1.18 · high 3.51 · good 29.80 · good Fair
Mon 17:00 1.16 · high 3.00 · good 29.80 · good Fair
Mon 18:00 1.16 · high 2.16 · good 29.70 · good Fair
Mon 19:00 1.14 · high 1.95 · good 29.70 · good Poor
Mon 20:00 1.12 · high 1.40 · good 29.60 · good Poor
Mon 21:00 1.06 · high 1.43 · good 29.50 · good Poor
Mon 22:00 1.04 · high 1.54 · good 29.60 · good Poor
Mon 23:00 1.02 · high 1.52 · good 29.50 · good Poor
Tue 00:00 1.02 · high 1.19 · good 29.50 · good Poor
Tue 01:00 1.00 · high 1.17 · good 29.50 · good Poor
Tue 02:00 1.00 · high 0.32 · good 29.50 · good Poor
Tue 03:00 1.00 · high 0.28 · good 29.50 · good Poor
Tue 04:00 0.98 · high 0.35 · good 29.50 · good Poor
Tue 05:00 0.98 · high 0.35 · good 29.50 · good Poor
Tue 06:00 0.98 · high 0.32 · good 29.50 · good Poor
Tue 07:00 0.98 · high 0.51 · good 29.50 · good Poor
Tue 08:00 0.98 · high 0.61 · good 29.50 · good Poor
Tue 09:00 0.98 · high 1.43 · good 29.50 · good Poor
Tue 10:00 0.98 · high 2.17 · good 29.60 · good Fair
Tue 11:00 0.98 · high 2.39 · good 29.70 · good Fair
Tue 12:00 0.98 · high 2.34 · good 29.80 · good Fair
Tue 13:00 0.98 · high 2.41 · good 29.90 · good Fair
Tue 14:00 0.98 · high 2.73 · good 30.00 · good Fair
Tue 15:00 0.96 · high 2.21 · good 30.10 · good Fair
Tue 16:00 0.96 · high 2.09 · good 30.10 · good Fair
Tue 17:00 0.96 · high 0.57 · good 30.10 · good Fair
Tue 18:00 0.96 · high 0.43 · good 30.00 · good Fair
Tue 19:00 0.96 · high 0.16 · good 29.90 · good Poor
Tue 20:00 0.96 · high 0.11 · good 29.80 · good Poor
Tue 21:00 0.92 · high 0.70 · good 29.70 · good Poor
Tue 22:00 0.94 · high 0.68 · good 29.60 · good Poor
Tue 23:00 0.94 · high 0.41 · good 29.60 · good Poor
Wed 00:00 0.94 · high 0.05 · good 29.50 · good Poor