San Diego Water Temperature by Month: When to Dive Dry

San Diego's surface water averages about 57 to 59°F in winter and 66 to 68°F in late summer, based on long-term measurements at Scripps Pier in La Jolla. It's often colder at depth, especially below the summer thermocline. Many local divers use a drysuit year-round; others dive a 7 mm wetsuit with a hood and gloves in summer.

By Jeremiah Gardner · Last reviewed October 28, 2026

San Diego has a reputation for sunshine, but its ocean is cool all year. Knowing what the water will be, at the surface and at depth, decides what you wear and how much you enjoy the dive.

Average water temperature by month

These are historical surface-temperature averages from Scripps Pier in La Jolla, compiled from NOAA's Coastal Water Temperature Guide by Current Results. UC San Diego Scripps Shore Stations publishes more recent station observations. These are averages, not a forecast. For today's reading, see La Jolla dive conditions.

Month	Average surface temperature
January	58°F
February	57°F
March	58°F
April	59–60°F
May	61–63°F
June	64–65°F
July	66–67°F
August	68°F
September	66°F
October	63–65°F
November	61°F
December	59°F

Where a range appears, the historical compilation distinguishes the first and second half of the month. Individual days and years can differ substantially. Check current surface and expected at-depth temperatures when choosing exposure protection.

Is it colder at depth?

Often, yes. In summer, the sun warms the surface layer, and a thermocline separates it from colder water below. You can descend through it and feel the temperature drop by several degrees within a few feet.

The local site Divebums describes summer water at depth from the low 60s to the high 60s, sometimes into the low 50s, and winter water at depth from the very low 50s to the high 50s, occasionally 49°F. Plan your exposure for the bottom of the dive, not the top.

When should you dive dry?

There's no single cut-off, but these are the situations where a drysuit makes the biggest difference:

Winter and spring, when the water is in the 50s.
Long dives, where cold builds up over time.
Deep dives, below the thermocline and where a wetsuit compresses and loses insulation.
Repetitive dives and training days, when you're in and out of the water for hours.

Many San Diego divers dive dry all year. Others use a 6 or 7 mm wetsuit with a hood and thick gloves in summer. Being cold costs more than comfort: it makes you breathe harder, and it makes fine control harder.

What changes when you switch to a drysuit?

Buoyancy, weighting and trim. A drysuit holds a bubble of gas that moves to the highest point, and its undergarments usually mean more lead. Redo your weight check whenever you change suits or undergarments, and learn the emergency skills before you need them. See Drysuit Buoyancy and Trim.

A drysuit also changes your options for heavier rigs. UTD requires a balanced exposure system such as a drysuit for steel doubles, unless the tanks are neutral or positive at 500 psi. In my classes, steel never goes with a wetsuit.

Stay warm, stay sharp

Cold divers make slow decisions. Plan your thermal protection for the coldest part of the dive and the full time in the water, including the exit. If you use a heated vest on long drysuit dives, your undergarments still need to keep you warm enough to finish the dive if the heat fails.

Learn to dive dry

Our Drysuit Diver course covers drysuit buoyancy, emergency procedures and suit care. For where to dive once you're warm, see DIR and Technical Diving in San Diego and La Jolla Shores for Skills Practice.

Frequently asked questions

When is the water warmest in San Diego?

August, on long-term averages, at about 68°F at the surface. July through October is the warmest stretch, though water at depth can be much colder.

When is the water coldest?

February is the coldest month on long-term averages, at about 57°F at the surface. Expect colder water at depth.

Do I need a drysuit to dive in San Diego?

No, but many local divers use one, especially in winter or for long, deep or repeated dives. A 7 mm wetsuit with a hood and gloves works for many divers in summer.

Why is it colder at depth in summer?

The sun warms the surface layer, and a thermocline separates it from colder water below. On a summer dive, you can drop through it and lose several degrees in a few feet.