San Jose sits at the southern end of San Francisco Bay in northern California, in the Santa Clara Valley sheltered by the Santa Cruz Mountains at approximately 37.34°N, 121.89°W. It has a warm-summer Mediterranean climate (Köppen Csb) — with warm, bone-dry summers and mild, wet winters — and it is remarkably sunny and dry.

Summer, from June to September, is warm, sunny and utterly rainless, with July and August the warmest — average highs around 28–29°C — with very low humidity and cool nights, as marine air drifts in from the bay. Genuinely hot spells occur but are brief, and the Santa Cruz Mountains shield the valley from the coastal fog that shrouds San Francisco.

Winter, from December to February, is mild and the wet season, with January the coolest month — average highs around 15–16°C and lows near 5°C, with frost occasional. Pacific storms bring nearly all of the year's rain, though sunny spells are frequent between fronts, and the season is comfortably mild.

San Jose is dry, receiving only around 380–400 mm of rain a year — less than most of coastal California — because the Santa Cruz Mountains cast a rain shadow over the Santa Clara Valley; almost all of it falls between November and March, while the summer is entirely rainless. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.

San Jose sits in the rain shadow of the Santa Cruz Mountains, which strip the moisture from incoming Pacific storms and shelter it from the fog that grips San Francisco just 80 km north — giving Silicon Valley a notably sunnier, warmer, drier climate than the coast, with around 300 sunny days a year.

To follow any single measurement in San Jose more closely, use our live instruments: the online barometer for atmospheric pressure, the thermometer for temperature, the hygrometer for humidity, the anemometer for wind speed, the wind vane for wind direction, and the rain gauge for rainfall.