Weather in San Jose in August

Prime time. August is about as good as San Jose gets. Highs average 31.6 °C, lows 13.7 °C, and rain falls on 0 days — nothing in the month is working against you.

August ranks 8 of 12 in San Jose: past the worst of the year but short of May, which is the month to book if the dates are open.

Rain is not a factor worth planning around this month. Pack for 31.6 °C days and 13.7 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: 7 days clear 35 °C, so a serious heatwave is normal rather than notable; the day swings 17.9 °C from low to high, which means one bag has to cover both. Across the twenty years measured, the hottest August day reached 44.1 °C and the coldest night fell to 9.4 °C.

August is dependably dry, and that reliability is the point: across the twenty years measured, the wettest August on record still only managed 6 mm, and the driest managed 0 mm. There is no meaningful variability to plan around, which makes this one of the few months anywhere that you can build a fixed outdoor itinerary against without a fallback. The wettest single day in twenty years of Augusts brought 1 mm. Rain simply is not the variable that decides this trip — heat, crowds and cost are.

Wind is light at 9.2 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 63%.

How August sits in the year

Temperatures hold steady either side: 31.2 °C in July, 31.6 here, 31 in September. Nothing about the timing within the month matters much.

Daylight in August

13.6 hours of daylight, losing 1 hours across the month. That is between San Jose's extremes of 14.7 and 9.6 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 15.2 °C in August — cold — a quick dip rather than a swim, and a wetsuit if you are in for longer. This is the warmest the water gets all year.

How busy it gets

Busy. Popular without being frantic; book the things you care about, improvise the rest.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

August in San Jose versus nearby

If San Jose is one option among several, the nearby comparison is worth making. San Francisco is a better bet in August — 8 °C cooler, the same number of rain days. Napa is the weaker option in August — 2.2 °C warmer, the same number of rain days.

So: August works, with May the better month by 16 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in San Jose

See all twelve months in San Jose, or where else to go in August.