The best time to dive, month by month, for every dive region

Name: Best-time-to-dive monthly scores by dive region
Creator: OpenWaterAtlas
License: https://creativecommons.org/licenses/by/4.0/

"Best time to visit" advice is usually one person's memory of one trip — and it's almost always pitched at whole countries, which is the wrong grain: the Pacific and Caribbean coasts of Mexico don't share a season. So this scores every month from 5 years of daily wind, rain and temperature across 1,277 dive sites, grouped into 98 dive regions (by nearest travel hub) in 23 countries. Darker = the calmer, drier, warmer weeks each region's own conditions favour. Built from our open dataset — reproducible, not a guess.

Indonesia: 6 months apart

Sorong peaks in November, but Jakarta in May — a single "best month" for the country would hide that.

🇪🇨 Isla Baltra

is the most year-round region here — the flattest swing between its calmest and roughest months.

🇺🇸 Monterey

has the sharpest season — its best months stand out most, so timing matters there.

Dive region	J	F	M	A	M	J	J	A	S	O	N	D	Best months
🇮🇩 Indonesia
Sorong 65	Fair	Low	Fair	Good	Low	Low	Low	Low	Low	Peak	Peak	Fair	October, November
Mataram (Pujut, Lombok Tengah) 42	Low	Low	Low	Peak	Peak	Good	Good	Good	Good	Good	Good	Low	April, May
Manado 34	Low	Low	Low	Low	Good	Good	Good	Peak	Peak	Peak	Low	Low	August, September, October
Luwok 32	Low	Low	Low	Fair	Low	Low	Low	Fair	Peak	Peak	Good	Low	September, October
Kuta, Badung 31	Low	Low	Good	Peak	Good	Good	Good	Good	Good	Peak	Peak	Fair	April, October, November
Bima 28	Low	Low	Low	Good	Good	Good	Good	Good	Good	Peak	Peak	Low	October, November
Jakarta 20	Low	Low	Low	Good	Peak	Good	Good	Peak	Good	Peak	Low	Low	May, August, September, October
Banda Aceh 3	Low	Good	Good	Peak	Good	Good	Low	Good	Good	Low	Low	Low	April
🇪🇬 Egypt
Hurghada 86	Low	Low	Low	Good	Fair	Fair	Peak	Good	Good	Peak	Peak	Good	July, November
Berenice Troglodytica 57	Low	Low	Low	Low	Low	Low	Peak	Fair	Low	Low	Good	Low	July
Sharm El Sheikh 41	Good	Good	Good	Good	Good	Fair	Good	Good	Good	Peak	Good	Good	October
Marsa Alam 31	Fair	Fair	Low	Fair	Fair	Fair	Peak	Good	Fair	Peak	Good	Good	July, October
Saint Catherine 21	Good	Good	Good	Good	Good	Good	Peak	Good	Good	Good	Peak	Good	July, November
🇲🇻 Maldives
Malé 94	Good	Good	Peak	Peak	Low	Good	Low	Low	Low	Low	Low	Low	March, April
Maamigili 40	Good	Good	Peak	Peak	Low	Good	Low	Low	Low	Low	Low	Low	March, April
Gan 8	Good	Good	Peak	Good	Low	Good	Low	Good	Good	Low	Low	Low	March, June
Noonu Atoll 8	Good	Good	Peak	Peak	Low	Good	Low	Low	Low	Low	Low	Low	March, April
🇵🇭 Philippines
Coron 18	Good	Good	Good	Peak	Good	Fair	Low	Low	Low	Low	Good	Good	April
Mamburao 17	Good	Good	Good	Peak	Peak	Fair	Low	Low	Low	Fair	Good	Good	April, May
Ormoc City 14	Low	Low	Good	Good	Peak	Peak	Low	Good	Low	Low	Fair	Low	May, June
Dumaguete City 11	Good	Good	Good	Peak	Good	Fair	Low	Good	Fair	Low	Low	Low	April
Cabatuan 10	Good	Good	Good	Peak	Good	Low	Low	Low	Low	Low	Low	Low	April
Panglao 7	Low	Low	Good	Peak	Good	Fair	Low	Fair	Fair	Low	Low	Low	April
Surigao City 4	Low	Low	Fair	Good	Good	Peak	Low	Low	Fair	Fair	Low	Low	June
Davao 3	Low	Low	Good	Peak	Low	Low	Low	Low	Fair	Good	Fair	Low	April
Mambajao 3	Low	Low	Low	Good	Good	Peak	Fair	Peak	Good	Fair	Low	Low	May, June, August, September
🇫🇷 France
Hyères, Var 13	Low	Low	Low	Low	Low	Good	Good	Peak	Good	Low	Low	Low	August
Cannes 10	Low	Low	Low	Low	Good	Good	Good	Peak	Good	Low	Low	Low	July, August
Papeete 8	Low	Fair	Peak	Good	Good	Low	Good	Low	Low	Low	Low	Low	March
Biarritz 5	Low	Low	Low	Low	Low	Good	Peak	Peak	Good	Low	Low	Low	July, August
Bordeaux 5	Low	Low	Low	Low	Low	Good	Peak	Peak	Good	Low	Low	Low	July, August
Le Castellet, Var 5	Low	Low	Low	Low	Low	Good	Good	Peak	Good	Low	Low	Low	August
Pointe-à-Pitre 5	Good	Good	Good	Peak	Good	Good	Good	Good	Peak	Fair	Good	Good	September
Grand-Bourg 4	Fair	Fair	Fair	Peak	Peak	Low	Low	Good	Peak	Fair	Fair	Fair	April, May, September
Perpignan/Rivesaltes 4	Low	Low	Low	Low	Good	Peak	Good	Peak	Good	Good	Low	Low	June, August
Brest 3	Low	Low	Low	Fair	Fair	Peak	Good	Peak	Fair	Low	Low	Low	June, August
Hondarribia 3	Low	Low	Low	Low	Low	Good	Peak	Peak	Low	Low	Low	Low	July, August
Montpellier/Méditerranée 3	Low	Low	Low	Low	Good	Good	Good	Peak	Good	Low	Low	Low	August
🇹🇭 Thailand
Na Thon (Ko Samui Island) 20	Good	Good	Good	Peak	Low	Low	Low	Low	Low	Low	Low	Low	April
Phuket 15	Good	Good	Good	Peak	Low	Low	Low	Low	Low	Low	Low	Good	April
Langkawi 9	Low	Good	Good	Peak	Good	Good	Good	Low	Low	Low	Low	Low	April
Ranong 8	Good	Good	Good	Peak	Low	Low	Low	Low	Low	Low	Low	Low	April
Laem Ngop 7	Good	Good	Good	Peak	Fair	Low	Low	Low	Low	Low	Good	Good	April
Krabi 6	Good	Good	Good	Peak	Fair	Low	Low	Low	Low	Low	Low	Good	April
🇺🇸 United States
Pensacola 11	Low	Fair	Low	Good	Fair	Fair	Peak	Fair	Good	Fair	Low	Fair	July
Monterey 10	Low	Low	Low	Low	Fair	Good	Good	Peak	Peak	Good	Low	Low	July, August, September
Kahului 8	Good	Good	Good	Good	Good	Good	Good	Good	Good	Peak	Good	Good	October
Burlington 6	Fair	Low	Low	Low	Fair	Good	Good	Good	Peak	Low	Low	Low	September
Gainesville 6	Fair	Good	Good	Good	Good	Good	Good	Fair	Good	Peak	Good	Good	October
San Jose 5	Low	Low	Low	Low	Low	Good	Peak	Peak	Peak	Good	Low	Low	July, August, September
Hagåtña 4	Good	Good	Good	Good	Peak	Peak	Fair	Fair	Fair	Low	Good	Good	May, June
Hilo 4	Good	Low	Low	Low	Low	Good	Low	Low	Peak	Peak	Low	Low	September, October
Panama City Beach 3	Low	Low	Low	Good	Good	Low	Low	Low	Fair	Peak	Fair	Low	October
San Juan 3	Peak	Good	Good	Good	Peak	Good	Good	Good	Good	Peak	Good	Peak	January, May, October, December
🇭🇷 Croatia
Rijeka(Omišalj) 29	Low	Low	Low	Low	Low	Peak	Good	Good	Low	Low	Low	Low	June
Pula 11	Low	Low	Low	Low	Low	Peak	Good	Good	Low	Low	Low	Low	June, July
Zadar 10	Low	Low	Low	Low	Low	Peak	Good	Good	Good	Low	Low	Low	June
Split 5	Low	Low	Low	Low	Low	Peak	Good	Good	Good	Fair	Low	Low	June
Sečovlje 3	Low	Fair	Low	Fair	Low	Peak	Good	Good	Low	Low	Low	Fair	June
🇦🇺 Australia
Cairns 11	Low	Low	Low	Low	Low	Low	Low	Low	Low	Good	Peak	Fair	November
Williamtown 9	Good	Good	Good	Good	Fair	Fair	Fair	Good	Good	Good	Good	Peak	December
Sydney (Mascot) 8	Low	Good	Low	Peak	Good	Good	Fair	Fair	Fair	Good	Good	Good	April
Geelong/Melbourne 7	Fair	Good	Peak	Good	Good	Low	Low	Low	Low	Low	Low	Low	March
Grafton 5	Good	Good	Low	Low	Low	Peak	Low	Fair	Low	Low	Fair	Good	June
Perth 4	Fair	Good	Good	Peak	Good	Low	Low	Low	Fair	Fair	Good	Fair	April
Gold Coast 3	Good	Low	Low	Good	Low	Peak	Fair	Fair	Good	Good	Low	Good	June
🇮🇹 Italy
Genova (GE) 20	Low	Low	Low	Low	Low	Peak	Peak	Peak	Low	Low	Low	Low	June, July, August
Alghero 6	Low	Low	Low	Fair	Good	Peak	Peak	Peak	Good	Good	Low	Low	June, July, August
Rome 6	Low	Low	Low	Low	Good	Peak	Good	Peak	Good	Low	Low	Low	June, August
Reggio Calabria 4	Low	Low	Low	Low	Good	Peak	Peak	Good	Good	Good	Low	Low	June, July, August
Campo nell'Elba (LI) 3	Low	Low	Low	Low	Fair	Good	Peak	Good	Good	Low	Low	Low	July
Grosseto (GR) 3	Low	Low	Low	Low	Fair	Good	Good	Peak	Good	Low	Low	Low	August
Olbia (SS) 3	Low	Low	Low	Low	Good	Peak	Peak	Peak	Good	Good	Low	Low	June, July, August
🇬🇧 United Kingdom
Brighton, East Sussex 25	Low	Low	Low	Fair	Fair	Peak	Good	Peak	Low	Low	Low	Low	June, July, August
Kirkwall, Orkney Islands 10	Low	Low	Low	Fair	Fair	Fair	Good	Fair	Low	Low	Low	Low	May, July
🇲🇽 Mexico
Cozumel 24	Good	Good	Good	Good	Good	Low	Good	Good	Peak	Good	Good	Good	September
Cancún 5	Low	Low	Low	Fair	Good	Low	Peak	Peak	Good	Good	Good	Low	July, August
San José del Cabo 3	Good	Good	Good	Good	Peak	Good	Good	Good	Good	Good	Good	Peak	May, December
🇵🇹 Portugal
Lisbon 17	Low	Low	Low	Low	Low	Low	Good	Good	Peak	Low	Low	Low	September
Porto 6	Low	Low	Low	Low	Low	Good	Good	Peak	Good	Low	Low	Low	August
Portimão 5	Low	Low	Low	Fair	Fair	Fair	Fair	Fair	Peak	Good	Fair	Low	September
Cascais 4	Low	Low	Low	Low	Low	Low	Good	Good	Peak	Fair	Low	Low	September
🇲🇹 Malta
Valletta 31	Low	Low	Low	Low	Low	Good	Peak	Peak	Good	Good	Low	Low	June, July, August
🇨🇴 Colombia
San Andrés 17	Low	Low	Good	Peak	Good	Low	Low	Fair	Peak	Good	Low	Low	September
🇨🇾 Cyprus
Paphos 6	Low	Low	Low	Good	Good	Good	Peak	Good	Good	Good	Good	Low	July
Lefkoniko (Geçitkale) 5	Low	Low	Low	Good	Good	Good	Good	Good	Peak	Peak	Good	Low	September, October
Larnaca 3	Low	Low	Low	Good	Good	Good	Good	Good	Good	Peak	Peak	Low	October, November
🇪🇨 Ecuador
Isla Baltra 7	Peak	Peak	Good	Good	Good	Good	Good	Good	Good	Good	Good	Good	January, February
Salinas/La Libertad 4	Good	Fair	Good	Peak	Good	Good	Good	Good	Good	Good	Good	Good	April
🇨🇻 Cape Verde
Espargos 6	Low	Low	Low	Low	Low	Good	Peak	Good	Good	Good	Good	Low	July
São Pedro 3	Good	Low	Good	Good	Low	Low	Peak	Good	Good	Good	Good	Good	July
🇲🇦 Morocco
Rabat 5	Low	Low	Low	Low	Good	Good	Peak	Peak	Good	Good	Fair	Low	July, August
Essaouira 3	Fair	Good	Good	Good	Good	Good	Good	Peak	Peak	Peak	Peak	Good	August, September, October, November
🇦🇷 Argentina
Mar del Plata 4	Good	Low	Low	Low	Fair	Fair	Fair	Fair	Fair	Fair	Low	Low	May
La Plata 3	Good	Good	Good	Fair	Fair	Fair	Fair	Low	Low	Low	Good	Good	June
🇹🇿 Tanzania
Zanzibar 4	Good	Good	Good	Low	Good	Good	Good	Good	Good	Good	Good	Peak	December
🇲🇺 Mauritius
Plaine Magnien 3	Low	Good	Good	Peak	Good	Low	Low	Low	Low	Good	Peak	Good	April, November
🇹🇷 Turkey
Bodrum 3	Low	Low	Low	Fair	Good	Good	Good	Peak	Good	Peak	Low	Low	August, October

Rating vs. each region's own year, plus fixed comfort thresholds: Peak Good Fair Low "Low" = that region's off-season, not "bad diving". Number after a region = dive sites in it. Hover a cell for the underlying wind / rain / temperature.

How the regions and the score are built

A country is too coarse a unit — Mexico spans the Pacific and the Caribbean, the US spans Florida, California and Hawaii. We don't hold administrative regions, so each dive site is snapped to its nearest airport hub (within 150 km) and regions are named by that hub city — Cozumel, Cabo, Kona, Key West — which is how you'd fly there anyway. Sites more than 150 km from any hub (remote liveaboard reefs like Socorro) are left out.

For each site we hold a 5-year daily climatology — median wind, mean rain and mean air temperature per day — from Open-Meteo / ERA5. We average those to a monthly value per region, then score each month on three things a diver feels:

Calm — lower wind means better visibility, easier boat access and less surge.
Dry — less rain means less runoff killing viz, and fewer blown-out days.
Warm — warmer air tracks warmer water (weighted at half, since divers tolerate warmth far better than cold).

Each factor is z-normalised within the region and combined. Every month is then rated Peak / Good / Fair / Low by how far it sits from that region's own best month — so the rating answers "which months are best for this region", not a global ranking, and a genuinely year-round region never drops to "Low". A relative score alone over-reacts where conditions barely change, so we also apply fixed diver thresholds (rain above ~3 mm/day, wind above ~13 kn, air below ~25°C): a month that is comfortable in absolute terms is rated at least Good, and a month that is rough in absolute terms is capped at Fair. A region needs at least 3 sites with climatology to appear (98 qualify today).

Caveats, stated plainly. This is a climate-conditions signal, not a marine-life calendar — a manta or whale-shark season can peak outside the calmest weeks. Water temperature is inferred from air, not measured per month. Regions are approximated by airport proximity, not surveyed dive-operator boundaries. And climate is the long-run average; any single year varies. Every input is in the open dataset, so you can re-derive or re-weight this yourself.

Get the open dataset (CC-BY 4.0) Country dive guides

Data: OpenWaterAtlas open dataset (DOI 10.5281/zenodo.20668393), built on Open-Meteo / ERA5. CC-BY 4.0 — reuse with attribution and a link back.