Best Time to Visit San Diego

The best time to visit San Diego is August to October, our pick for warm days and warm water. NOAA's 1991–2020 normals show an average high of 77.3 F in August and 77.2 F in September, and San Diego Bay water averages 72.1 F in August. If you want gray whales instead, go from mid-December to March, with the peak in mid-January.

Weather by month

Note: Temperatures, rain and rain days are NOAA NCEI 1991–2020 monthly normals for station USW00023188, San Diego Lindbergh Field, pulled from the NCEI data API on 15 Oct 2026. Rain days count days with 0.10 inch or more. Water temperature is the monthly average for the San Diego Bay gauge (station 9410170) from NCEI's Coastal Water Temperature Guide (read 15 Oct 2026; the page does not state the averaging years)

Lindbergh Field is next to the bay. Places a few miles inland run hotter in summer and colder at night. We did not pull inland stations.

May Gray and June Gloom

Note: The National Weather Service in San Diego explains it in its Weather Guide (6th edition, 2012, read 15 Oct 2026). The ocean along the coast is cool. When the air above the water is warmer than the water, which is most common in late spring and early summer, a temperature inversion forms. The cooler air under it is called the marine layer, and it makes stratus cloud. "Because of its persistence in late spring and early summer, we often refer to it as the May Gray or June Gloom." NOAA's JetStream page (updated 2 May 2023) says the same thing in short form

In plain words: the sea is cold, the air is not, and the cloud sits on the coast. It is not rain. NOAA's normals give 0.28 inches in May and 0.05 inches in June. We did not find an official count of gray days per month, so we cannot tell you how many to expect.

Whale watching

Note: NPS, Cabrillo National Monument "Whale Watching" page in the park's nature section (last updated 28 Jul 2024, read 15 Oct 2026): whales are visible "from mid- to late December through March." "Mid-January is the peak time for migration." Look west from the overlooks. Whales travel from north (your right) to south (your left). Most swim from the kelp beds, about three-quarters of a mile out, to the horizon

Note: The park's plan-your-visit whale page (last updated 28 Sep 2023, read 15 Oct 2026) gives a shorter window: "late December to mid March". It does not name a peak

The two NPS pages agree on late December to mid-March. Our advice is to aim for January, the peak on the newer page. We did not check boat tour operators, prices or sailing dates. Sightings vary by year, and we found no official count for this winter.

Events with dates

Note: Comic-Con International, comic-con.org (read 15 Oct 2026): "We look forward to seeing you next year on July 22-25, with Preview Night on July 21." The same page lists the 2027 returning registration badge sale on 17 October 2026 and open registration on 14 November 2026. The page does not name the venue

Note: San Diego County Fair, sdfair.com tickets page (read 15 Oct 2026): the 2026 fair ran 10 June to 5 July, closed Mondays and Tuesdays, at the Del Mar Fairgrounds, 2260 Jimmy Durante Blvd. We did not find 2027 fair dates, so those are not confirmed

If you do not hold a Comic-Con badge, treat 21 to 25 July 2027 as a week to plan around. This is our advice. We did not check hotel rates for those dates.

Crowds

No official monthly visitor count was read for this page. Our estimate: summer is the busy season, because school is out and the water is warmest. Late September and October should be quieter, with the same air temperature. This is our reasoning, not data.

Santa Ana winds and fire season

Note: NWS San Diego Weather Guide (2012, read 15 Oct 2026): Santa Ana winds are "strong, dry offshore winds that blow from the east or northeast." They "occur mainly during fall and winter and are most common during December. Summer events are rare." A reasonably strong event can give sustained winds of 30 to 40 mph with gusts over 60 mph. "There is always a high fire danger during these events." Fall events can bring hot weather, and most coastal high temperature records came during a hot Santa Ana

Check weather.gov/sgx for Red Flag Warnings on the day. We did not check this week's forecast.

The worst time to go

There is no bad month for the weather. These are the times we would avoid, depending on what you want.

• Late July 2027, if you are not going to Comic-Con. Dates are official. The effect on hotel rates and crowds is our guess.

• May and June, if you want a sunny beach day. The coast is often gray.

• A Santa Ana day in fall or winter, if you plan to hike inland. Fire danger is high and gusts can be strong.

What we checked and what can change

• NOAA NCEI 1991–2020 normals, USW00023188, pulled from the NCEI data API on 15 Oct 2026. Normals are 30-year averages, not a forecast.

• NCEI Coastal Water Temperature Guide, San Diego Bay row, read 15 Oct 2026. The page did not state the averaging years.

• NWS San Diego Weather Guide (6th edition, 2012, by forecaster Miguel Miller), PDF on weather.gov, read 15 Oct 2026. The quotes on this page are in it, but it is now several years old.

• NOAA JetStream marine layer page, updated 2 May 2023, read 15 Oct 2026.

• NPS Cabrillo National Monument whale pages, the nature section page (updated 28 Jul 2024) and the plan-your-visit page (updated 28 Sep 2023), both read 15 Oct 2026.

• comic-con.org home page and sdfair.com tickets page, read 15 Oct 2026.

• Not confirmed: 2027 County Fair dates, hotel and flight prices, boat tour operators, monthly visitor counts, inland temperatures, number of gray days.