Sacramento, the capital of California, sits at the confluence of the Sacramento and American rivers in the flat Central Valley, sheltered between the Coast Ranges and the Sierra Nevada at approximately 38.58°N, 121.49°W. It has a hot-summer Mediterranean climate (Köppen Csa) — hot, bone-dry summers and mild, wet winters.

Summer, from June to September, is hot and utterly rainless, with July the hottest month — average highs around 34–35°C, with heatwaves exceeding 40°C — though the very low humidity and the delta breeze, which draws cool marine air in from San Francisco Bay each evening, make the nights pleasantly cool.

Winter, from December to February, is mild and the wet season, with January the coolest month — average highs around 13–14°C and lows near 4°C, with frost occasional. Pacific storms bring nearly all of the year's rain, and the valley traps dense tule fog, a thick ground fog that can persist for days and reduce visibility to metres.

Sacramento receives around 450–480 mm of rain a year, almost all of it between November and March, while June to September is essentially rainless — the classic Mediterranean pattern. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.

Sacramento's Central Valley setting produces two distinctive phenomena: the delta breeze, which pulls cool ocean air inland on summer evenings to relieve the heat, and tule fog, a dense winter ground fog that settles over the valley for days at a time and is a notorious driving hazard.

To follow any single measurement in Sacramento 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.