Forecast wind and seas are below the thresholds for the sites in this zone over the next six hours, no buoy is showing incoming swell, and no fresh report says otherwise. Normal operating day.
How to read the board
Every zone gets one of three verdicts for the next six hours. The verdict is rules-based, the rules are published, and a fresh report from an operator beats the model.
Something is near a limit: wind on the exposed side, a building sea, a long-period swell wrapping in, or the buoys showing swell on the way. Operators will likely still run but may change sites or cancel the second dive. Check with your shop.
Forecast wind or seas exceed the thresholds for this zone, a special rule has tripped (Sandbar closure wind, tender-suspending swell, a northerly on the North Wall), or a fresh operator report says it is rough or blown out. Expect cancellations and look at the other side of the island.
The wind arrow and meters on each card
The arrow points where the wind is blowing to; this one is a north-easterly. The meter under it fills with speed and turns amber at 16 kt and red at 22 kt when the wind is onto that zone (higher limits apply on a zone’s sheltered side). The seas meter does the same at 1.2 m and 2 m.
What the numbers feel like
| Wind | On the water |
|---|---|
| 0 to 10 kt | Glassy to light ripple. Everything is on. |
| 10 to 15 kt | Normal trade-wind day. Whitecaps offshore, lee sides flat. |
| 15 to 20 kt | Fresh. Exposed sides get bumpy; boats pick the lee. Sandbar starts to get marginal in a northerly. |
| 20 to 25 kt | Strong. Exposed sides are out; RCIPS closes the Sandbar in N or NE wind around here. |
| 25 plus kt | Small-craft territory. Only the most sheltered sites, if any. |
| Seas | On the water |
|---|---|
| under 0.6 m | Calm. Shore entries and tenders fine. |
| 0.6 to 1.2 m | Slight to moderate. Fine for boat dives on the lee; shore ladders get surgy if it is from the west. |
| 1.2 to 2.0 m | Rough on the exposed side. Tenders suspend on 1 m of W or NW swell. |
| 2.0 m plus | Exposed sides closed. Long-period swell (9 s plus) does more damage than its height suggests. |
Which side of the island
- Easterly trades (the normal state): West and George Town are flat, North Sound is fine, East End takes the swell.
- North or north-east wind (behind a cold front): North Wall and North Sound suffer first; the Sandbar closes near 22 kt. South Side and the south-east corner of East End are the lee.
- Nor’wester (west or north-west swell): the rare bad day for the west. George Town tenders suspend, Seven Mile shore entries surge, Spotts becomes the cruise landing. South Side is the refuge.
- Sister Islands: Bloody Bay and the Brac’s north shore close in north wind; operators move to the south shores.
Where the data comes from
- Hourly wind, gusts, seas, swell and water temperature from Open-Meteo’s weather and marine models, at one open-water point per zone, refreshed hourly.
- Tide from the same marine model’s sea level. Cayman’s tide is small (about 0.3 m) so it never changes a verdict, but it does change the Sandbar’s depth and clarity and how easy a reef-flat shore entry is, so it is shown as a line where that matters. Times are approximate; the official tables are on the CINWS sun and tides page.
- Observed wind from the Owen Roberts airport METAR, used for the current hour on Grand Cayman.
- Offshore buoys 42056 and 42057 as early warning for westerly swell. Neither is in Cayman waters.
- Your reports. An operator report overrides the model for about 3 hours; two agreeing public reports can downgrade a verdict.
There is no buoy, tide gauge or official data feed in Cayman waters, so this is a model plus local rules plus people. Official forecasts and warnings come from the Cayman Islands National Weather Service. The thresholds are published in the project repository and will be tuned against what operators actually do this winter.