When is the water warm enough to swim without a wetsuit?
August is the peak at about 68°F, with July and September close behind around 66–67°F. June is only 64–65°F despite feeling like summer — the water lags the air by roughly two months.
- Warmest month
- August, about 68°F
- Coldest month
- February, about 57°F
- Annual average
- 62°F
- Comfortable without a wetsuit
- Roughly June–October
Measured at Scripps Pier, La Jolla
For most people, for a real swim
The short version
- August is the warmest month in the water at about 68°F; February is the coldest at about 57°F.
- The swimmable stretch without neoprene is roughly June through October — five months of the year, not the whole summer.
- September holds 66°F, within two degrees of the August peak, with noticeably thinner beaches.
- June is the trap: the air is already summery at about 72°F while the water is still around 64°F.
- The annual average is 62°F, which is why locals own wetsuits and visitors don't understand why.
San Diego's ocean temperature is measured continuously at Scripps Pier in La Jolla, one of the longest-running coastal temperature records in the world — the series goes back to 1916. So this is not a guess or an average of holiday photographs. It is a number, and it is lower than almost everyone expects.
Ocean temperature by month
Average water temperature at Scripps Pier, La Jolla
Source: Current Results, from the National Oceanographic Data Center's Coastal Water Temperature Guide. Where the published figure is a range, the midpoint is plotted — open the data view for the exact monthly values.
Read the shape rather than the peak. The water clears 64°F in June and drops back under it in November: about five months of the year are swimmable without neoprene for most people, and the genuinely warm stretch — 67–68°F — is six or seven weeks long, from mid-July to early September.
Why June catches people out
Because the air gets there first. Put the two on the same axis and the gap is obvious: by June the coastal air high is around 72°F and rising toward its August peak, while the water is still sitting at 64°F, barely above where it was in May.
Air catches up to summer before the water does
Average coastal air high against ocean temperature, by month
Air: monthly average high for San Diego, Climates to Travel (converted from °C). Water: Current Results / NODC. Two different sources, both plotted in °F on one axis.
So September, then
September is the answer to a question most visitors don't think to ask. The water is 66°F — within two degrees of the annual peak — the marine layer has largely given up for the year, and the beaches empty out the week school goes back. If you have any flexibility about when you come and the water matters to you, this is the month.
68°F
August peak
Warmest water of the year
66°F
September
Two degrees cooler, far fewer people
11°F
Annual swing
February to August
What people actually wear
This part is a rule of thumb rather than a sourced fact — cold tolerance is personal, and how long you're in matters more than the number. But it is roughly what you'll see in the water:
| Water | Typical | What it feels like |
|---|---|---|
| 67–68°F | Board shorts / swimsuit | Bracing for a second, then fine |
| 64–66°F | Fine for a swim, shorty for an hour+ | Cold on entry, comfortable once moving |
| 60–63°F | Shorty or full 3/2 wetsuit | A quick dip is pleasant; an hour is not |
| 57–59°F | Full wetsuit for most people | This is why locals own neoprene |
A guide, not a measurement. Surfers sitting still get cold far faster than swimmers.
KEEP READING
SOURCES
Everything above traces back to one of these. Follow them — if one has changed and we haven't, that's our mistake, not yours.
Current Results / NOAA National Oceanographic Data Center · Checked September 8, 2026
Every monthly water temperature on this page, and the 62°F annual average.
Scripps Institution of Oceanography, UC San Diego · Checked September 8, 2026
The measurement programme the record comes from; daily observations at Scripps Pier since 1916.
Climates to Travel · Checked September 8, 2026
Monthly average air highs used in the air-versus-water chart, converted from °C.