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Is it good to dive Haad Yao Reef today?

59 Meh

Meh at Haad Yao Reef — experienced divers only

Sun 19 Jul · 2 of next 7 days divable

Observed wind 17 km/h NW Water clarity ~10 m

Today, Sun 19 Jul, Haad Yao Reef is a 'Meh' day — 59/100: moderate wind, strong current, fair visibility. Live 7-day dive conditions forecast for Haad Yao Reef in the Gulf of Thailand — useful for both freediving and scuba diving. Scored on wind (with per-site directional exposure), waves, swell, ocean current, visibility and tides. 4-model ensemble-averaged, calibrated by instructor reports.

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Last update: Sun 19 Jul, 13:11 UTC · Timezone shown: Asia/Bangkok

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Dive Site
Sun
19 Jul
Mon
20 Jul
Tue
21 Jul
Wed
22 Jul
Thu
23 Jul
Fri
24 Jul
Sat
25 Jul
Haad Yao Reef Koh Phangan · to 12m
59
Meh
23km/h · 0.4m
59
Meh
23km/h · 0.4m
60
Decent
20km/h · 0.4m
55
Meh
20km/h · 0.6m
55
Meh
23km/h · 0.5m
50
Meh
26km/h · 0.4m
60
Decent
25km/h · 0.3m
80–100 · Showtime
60–79 · Decent
40–59 · Meh
0–39 · Nope
Full Data Behind the Score

Every signal we use. Verify against your own readings — Windguru, Windy, your dive log. If it disagrees with reality, log your dive and we'll calibrate.

Date Scorei Windi Gusti Diri Wavesi Wave diri Periodi Swelli Currenti Cur diri SSTi Rain 7di Chl-ai Bloomi Tide rangei CAPEi Stormi Modelsi Spreadi Factorsi
Sun 19 Jul 59 23 21 W 0.36 W 2.5s 0.18 1.10 NE 30.9° 32.5 0.80 0.42 0.46 2520 extreme 4 7.4 strong current, thunderstorm risk (extreme)
pts 59/100 wind 21/30 waves 20/20 · swell 5/5 current 0/20 viz 13/20 tide 0 GFS 31.5 ICON 14.3 JMA 20.2 GEM 25.9
Mon 20 Jul 59 22.8 20.5 W 0.40 W 2.5s 0.22 1.00 NE 30.9° 31.2 0.80 0.42 0.33 2700 extreme 4 5.6 strong current, thunderstorm risk (extreme)
pts 59/100 wind 21/30 waves 20/20 · swell 5/5 current 0/20 viz 13/20 tide 0 GFS 28.8 ICON 15.4 JMA 24.5 GEM 22.3
Tue 21 Jul 60 20.3 19.5 W 0.40 SW 2.5s 0.18 0.80 NE 31.0° 23.0 0.80 0.42 0.19 2590 extreme 4 5.6 strong current, thunderstorm risk (extreme)
pts 60/100 wind 21/30 waves 20/20 · swell 5/5 current 0/20 viz 14/20 tide 0 GFS 25.3 ICON 12.3 JMA 22.4 GEM 21.2
Wed 22 Jul 55 20 20 W 0.56 W 2.7s 0.26 0.60 NE 31.0° 16.2 0.80 0.42 0.06 2580 extreme 4 3.4 strong current, thunderstorm risk (extreme)
pts 55/100 wind 21/30 waves 14/20 · swell 5/5 current 0/20 viz 15/20 tide 0 GFS 22.9 ICON 16.8 JMA 22.8 GEM 17.3
Thu 23 Jul 55 23.4 23.4 W 0.50 W 2.6s 0.26 0.70 NE 30.9° 14.0 0.80 0.42 0.08 2560 extreme 4 9.1 strong current, forecast uncertainty, thunderstorm risk (extreme)
pts 55/100 wind 21/30 waves 14/20 · swell 5/5 current 0/20 viz 15/20 tide 0 GFS 36.5 ICON 16.2 JMA 22.1 GEM 18.7
Fri 24 Jul 50 25.7 27.9 W 0.44 W 2.5s 0.30 0.70 NE 30.8° 16.1 0.80 0.42 0.21 2960 extreme 4 9.1 wind from exposed direction, strong current, forecast uncertainty, thunderstorm risk (extreme)
pts 50/100 wind 10/30 waves 20/20 · swell 5/5 current 0/20 viz 15/20 tide 0 GFS 37.3 ICON 16.7 JMA 20.5 GEM 28.4
Sat 25 Jul 60 24.6 30.2 W 0.30 W 2.4s 0.16 1.00 NE 30.7° 23.8 0.80 0.42 0.35 2590 extreme 4 9.5 strong current, forecast uncertainty, thunderstorm risk (extreme)
pts 60/100 wind 21/30 waves 20/20 · swell 5/5 current 0/20 viz 14/20 tide 0 GFS 35.9 ICON 19.5 JMA 14.4 GEM 28.4

Reading the table: Each row shows one day. Below the values, a points row breaks down where the score came from — e.g. wind 22/30 means you earned 22 of 30 possible wind-points. Click the small (i) icons next to any column header to see a plain-English explanation of what the metric means and how to read it.

Sources: Wind/gust/direction and CAPE ensemble-averaged across GFS, ICON, JMA and GEM models. Waves, swell, ocean current, SST from Open-Meteo Marine. Tides from WorldTides FES2022. Satellite water-clarity (Secchi depth) and chlorophyll from Copernicus Marine Service. Calibrated by instructor reports.

How the score works

Out of 100, weighted for what matters underwater (freediving + scuba):

  • Wind (30pts) — with per-site exposure: sheltered sites get credit when wind blows from the sheltered quarter.
  • Waves (20pts) — surface chop, boat-ride comfort.
  • Swell (5pts) — long-period groundswell is rare in this enclosed gulf, so it is a light penalty; local wind-chop (counted under Waves) is the real surface driver.
  • Ocean current (20pts) — from Open-Meteo Marine ocean currents. Matters for both sports.
  • Viz (20pts) — led by satellite Secchi depth (real water clarity), plus 7-day rainfall runoff, wave-stirred bottom sediment at shallow sites, and seasonal turbidity.
  • Spring-tide penalty (−0 to −5) — applies only to shallow coastal sites (≤20m).

Forecast is ensemble-averaged across four weather models (GFS, ICON, JMA, GEM). When they disagree by >8 km/h we flag "forecast uncertainty."

Sources & caveats

Data comes from Open-Meteo Marine, a four-model weather ensemble (GFS, ICON, JMA, GEM), and Copernicus satellite water-clarity. Hover a cell for full metrics. Local factors the models can't see — boat traffic at Sail Rock, plankton blooms for whale-shark season, thermocline depth — still matter. Text us on WhatsApp for same-day conditions from the crew.

Why we built this

The most accurate Gulf of Thailand dive forecast — because the existing ones aren't

For years we relied on Windguru, Windy, and local weather apps to decide whether to run our boats. Every one of them is built for sailors — not divers. They tell you the wind speed and the wave height. They don't tell you there's a 0.8 m/s current ripping through Sail Rock that'll make your dive miserable — freediving or scuba. They don't know a plankton bloom just crashed visibility. They don't care about the thermocline at 18m, the spring-tide pull, or whether your specific dive site is sheltered from today's wind.

So we built our own. This tracker blends four weather models (GFS, ICON, JMA, GEM — averaged together), Open-Meteo's ocean data (waves, swell, ocean currents, sea-surface temperature, wave direction and period), real tide predictions from WorldTides FES2022, satellite water-clarity (Secchi depth) from Copernicus Marine as a direct visibility proxy, and atmospheric storm energy (CAPE) for thunderstorm risk. Then we score it for what matters underwater — not generic weather.

The final layer is you. Every instructor and diver who logs a post-dive report — what they actually saw, the real visibility, the real current — calibrates the forecast. Over time, ground-truth beats any algorithm. If you're diving in the Gulf, drop your report. It takes 30 seconds and makes the next boat-load of divers safer.

Who’s calibrating the forecast

Top Divers

  1. 1 Dominic 6 logs · 3 sites 140 +140 this mo
  2. 2 Diego 2 logs · 1 sites 98 +98 this mo
  3. 3 Carmen Smeets 2 logs · 2 sites 88 +88 this mo

Top shop: 100 Degrees East · 140 points

Full Leaderboard + Log Your Dive

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For Website Owners

Embed our live forecast on your site — free

Hotels, dive shops, travel blogs, villa rentals — drop a live Gulf of Thailand dive forecast onto any page in 30 seconds. Always fresh (updated hourly), no setup, no API keys, no account.

  • ✓Any of 115 Gulf dive sites, or the 7-day overview
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WordPress (Gutenberg): Add a "Custom HTML" block, paste the code. Classic editor: switch to "Text" tab, paste.

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Frequently Asked Questions

Is it good to dive Haad Yao Reef today? +
Divable for experienced divers, but not ideal Haad Yao Reef. Today it's a 'Meh' (59/100): moderate wind, strong current, fair visibility. 2 of the next 7 days look divable (a score of 60+).
What are the dive conditions at Haad Yao Reef this week? +
Over the next 7 days at Haad Yao Reef, the dive score ranges 50–60 out of 100, with 2 divable days (60+). The tracker breaks down wind (with per-site directional exposure), waves, ocean current and satellite visibility for each day.
Will my Haad Yao Reef dive trip get cancelled? +
It's mixed — 2 of the next 7 days look divable (60+). Pick a green day on the tracker and confirm with the shop the morning of.
How accurate is the Gulf of Thailand dive conditions forecast? +
The forecast ensemble-averages four weather models (GFS, ICON, JMA, GEM), blends Open-Meteo Marine ocean data (waves, swell, ocean currents, SST), real tides from WorldTides FES2022, satellite water-clarity (Secchi depth) and chlorophyll from Copernicus Marine, and atmospheric storm energy. Visibility also factors in rainfall runoff and wave-stirred bottom sediment at shallow sites. Scores are tuned for diving — both freediving and scuba — prioritising ocean currents and visibility over generic marine forecasts. Instructors log actual conditions after each dive, which calibrates the model over time.
What does the dive condition score mean? +
0–100, and we label it in plain diver-speak. Above 80 is "Showtime" (flat seas, clear water, minimal current). 60–79 is "Decent" (divable with minor compromise). 40–59 is "Meh" (experienced divers only). Below 40 is "Nope" (the boat likely stays in).
Why is Sail Rock's score different from Windguru's wind forecast? +
Windguru reports raw wind. Our score weights wind 30, waves 20, swell 5, ocean currents 20, and visibility 20 — and our visibility blends satellite Secchi depth (real water clarity), rainfall runoff, wave-stirred bottom sediment and seasonal monsoon turbidity, not just wind. Plus spring-tide and gust penalties at shallow or exposed sites. Scuba divers and freedivers both care about currents and visibility as much as surface wind — most general marine forecasts ignore them.
When is the best diving season in Koh Samui and Koh Tao? +
March to May offers the calmest seas and peak whale shark season at Sail Rock, though plankton blooms can reduce visibility. June to September has good visibility and moderate weather. October to December brings the northeast monsoon with choppier conditions. Check the live tracker for day-specific scoring.
How do I report actual dive conditions to improve the forecast? +
Visit /conditions/log after your dive — submit observed visibility, current strength, thermocline depth, and an optional photo. Each report earns points, climbs the leaderboard, and improves the forecast calibration. Dive shops who submit their website get a public backlink.
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