MARINE REPORT / 72 HOURS

Tumon Bay Snorkel Report Today

Guam · Updated Mon 00:39 (ChST) · Source: Snapshot

The skinny

Marginal Data updated Mon 00:39 (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 02:00 (ChST)

Later today

Poor · 2.6/10

Mon 17:00 (ChST)

Next three days

Fair · 4.1/10

Tue 14:00 (ChST)

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

Score: 2.6/10

Best time: Mon 17:00

Main risk: Waves

Best morning signal: Mon 11:00 (Poor).

Best afternoon signal: Mon 17:00 (Poor). Peak afternoon wind is about 9.6 m/s.

Email me when it is good

Sunrise

06:11

Sunset

18:00

Water

27.8°C

Max air

29.7°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

❌ Poor conditions

Main blocker: Waves

Best available hours

  • Tue 14:00: Fair (0.41) · still limited by waves, tide/current
  • Tue 12:00: Fair (0.37) · still limited by waves, tide/current
  • Tue 16:00: Fair (0.36) · still limited by waves, tide/current

Why this verdict

Main blockers across the next 72 hours:

  • Waves (69 hours)
  • Tide/current (69 hours)
  • Darkness (45 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

Next early morning high tide: Tue 00:00

Mon 15:00, Tue 00:00, Tue 16:00

Nearby alternatives in Guam

No nearby alternatives available.

Advanced forecast data

Viewing historical data

Sat 02:00 – Tue 02:00 (ChST)

Previous day Yesterday Next day Live

Snorkel Score (selected 24h)

Best snorkel score is 0.45 around Sat 11:00; 6 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 1.16m to 1.32m).

Wind is at or below 5.4m/s in 23/24 sampled hours (range 1.63 to 5.58m/s).

Tides range from 0.25m to 0.73m; 1 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
Fair ⚠️ Fair
Fair ⚠️ Fair
Fair ⚠️ Fair
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
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
Poor ❌ Limited
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
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Poor ❌ Limited
Fair ⚠️ Fair
Poor ❌ Limited
Poor ❌ Limited
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
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
Sat 02:00 1.26 · high 4.45 · good 29.60 · good Poor
Sat 03:00 1.26 · high 4.65 · good 29.60 · good Poor
Sat 04:00 1.26 · high 3.54 · good 29.60 · good Poor
Sat 05:00 1.26 · high 3.18 · good 29.60 · good Poor
Sat 06:00 1.26 · high 2.94 · good 29.60 · good Poor
Sat 07:00 1.26 · high 3.58 · good 29.60 · good Poor
Sat 08:00 1.26 · high 4.96 · good 29.60 · good Poor
Sat 09:00 1.26 · high 5.58 · high 29.60 · good Poor
Sat 10:00 1.30 · high 3.72 · good 29.60 · good Fair
Sat 11:00 1.30 · high 1.63 · good 29.60 · good Fair
Sat 12:00 1.32 · high 2.88 · good 29.60 · good Fair
Sat 13:00 1.32 · high 4.28 · good 29.70 · good Poor
Sat 14:00 1.32 · high 4.79 · good 29.70 · good Poor
Sat 15:00 1.32 · high 5.28 · good 29.70 · good Poor
Sat 16:00 1.32 · high 2.47 · good 29.70 · good Fair
Sat 17:00 1.32 · high 2.74 · good 29.70 · good Fair
Sat 18:00 1.30 · high 3.61 · good 29.70 · good Fair
Sat 19:00 1.30 · high 3.83 · good 29.70 · good Poor
Sat 20:00 1.30 · high 3.82 · good 29.70 · good Poor
Sat 21:00 1.28 · high 3.40 · good 29.60 · good Poor
Sat 22:00 1.18 · high 2.76 · good 29.70 · good Poor
Sat 23:00 1.18 · high 1.63 · good 29.70 · good Poor
Sun 00:00 1.16 · high 2.47 · good 29.60 · good Poor
Sun 01:00 1.16 · high 3.48 · good 29.60 · good Poor
Sun 02:00 1.16 · high 2.97 · good 29.60 · good Poor
Sun 03:00 1.16 · high 3.66 · good 29.60 · good Poor
Sun 04:00 1.16 · high 3.51 · good 29.60 · good Poor
Sun 05:00 1.20 · high 2.14 · good 29.60 · good Poor
Sun 06:00 1.20 · high 2.42 · good 29.60 · good Poor
Sun 07:00 1.20 · high 2.76 · good 29.60 · good Poor
Sun 08:00 1.20 · high 3.16 · good 29.60 · good Poor
Sun 09:00 1.20 · high 3.90 · good 29.60 · good Poor
Sun 10:00 1.20 · high 4.31 · good 29.70 · good Poor
Sun 11:00 1.20 · high 2.56 · good 29.70 · good Fair
Sun 12:00 1.18 · high 0.72 · good 29.80 · good Fair
Sun 13:00 1.18 · high 0.57 · good 29.80 · good Fair
Sun 14:00 1.18 · high 0.76 · good 29.90 · good Fair
Sun 15:00 1.18 · high 1.20 · good 29.90 · good Fair
Sun 16:00 1.18 · high 2.52 · good 29.90 · good Fair
Sun 17:00 1.18 · high 1.96 · good 29.90 · good Fair
Sun 18:00 1.16 · high 2.01 · good 29.90 · good Fair
Sun 19:00 1.16 · high 1.70 · good 29.80 · good Poor
Sun 20:00 1.16 · high 1.55 · good 29.80 · good Poor
Sun 21:00 1.14 · high 1.45 · good 29.70 · good Poor
Sun 22:00 1.14 · high 1.12 · good 29.70 · good Poor
Sun 23:00 1.14 · high 1.35 · good 29.70 · good Poor
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