Best Time to Dive Maine
Across 7 Maine dive sites with multi-year conditions history, July historically shows the most favorable days — 87% of sampled days in the good band. The next-highest months are June (86%), August (85%) and September (76%). February historically shows the fewest favorable days (31% of sampled days). Average water temperature in the sample runs from about 4°C in February to 18°C in August. Typical seas range from 0.8 m to 1.5 m of significant wave height through the year. These figures are historical climatology computed from measured conditions — patterns, not a forecast or a guarantee.
Computed from our own conditions climatology — measured history, not brochure copy.
Which months are historically most favorable in Maine?
| Month | Historically favorable days | Water temp | Typical seas |
|---|---|---|---|
| Jan | 41% | 5°C | 1.4 m |
| Feb | 31% | 4°C | 1.3 m |
| Mar | 38% | 4°C | 1.5 m |
| Apr | 59% | 6°C | 1.2 m |
| May | 74% | 10°C | 1.1 m |
| Jun | 86% | 15°C | 0.8 m |
| Jul | 87% | 17°C | 0.8 m |
| Aug | 85% | 18°C | 0.9 m |
| Sep | 76% | 18°C | 1.1 m |
| Oct | 57% | 14°C | 1.2 m |
| Nov | 51% | 10°C | 1.2 m |
| Dec | 38% | 7°C | 1.4 m |
% = share of sampled days scoring in the favorable band, median across 7 dive sites with at least two years of history. Ringed = historical peak.
How does this compare worldwide? The Most Reliable Diving Months on Earth ranks 61 countries by the same measure.
Marine life seasons
Sighting patterns across the wider US & Canada — Atlantic coast region — not site-specific promises.
- Scalloped hammerheadAugust
- Great white sharkAug–Sep
- Giant oceanic manta rayJul–Sep
- OrcaMay–Aug
- Humpback whaleJun–Aug
Bars are Jan–Dec — months when sightings historically concentrate (GBIF occurrence records). Wildlife is never guaranteed.
Diving Maine soon? Browse its dive sites with auto-updating 7-day condition windows — free, no account needed.
Choosing between destinations? Compare them month by month with the Trip PlannerPro