Berkeley Hills - Climatic Effects

Climatic Effects

The Berkeley Hills affect the local climate by their elevation. The oceanic marine layer, which develops during the summer is usually less than 2,000 feet deep and thus is blocked by the range. This produces a "fog shadow" effect to the east which is warmer than areas west of the hills. The westerly wind that carries the marine layer through the Golden Gate typically splits its flow as it hits the Berkeley Hills producing a southerly wind from Berkeley northward and a northerly flow in the direction of Oakland.

In winter during spells of tule fog inland, a reverse situation occurs, with the fog usually confined to areas east of the hills, although occasionally, the inland fog will pour in from the north, around the hills by way of the Carquinez Strait.

The Berkeley Hills affect rainfall; when the wind is perpendicular to the hills (southwest wind) during rain, air is forced to rise, cooling and condensing additional moisture, increasing the precipitation on the western slopes and leaving areas east of the hills drier. A cold storm will deposit wet snow on the peaks.

In spring and fall, sinking air from aloft combining with inland high pressure periodically sends hot, dry, and gusty winds across the ridges of the Berkeley Hills, posing a fire danger, which in the 20th century produced several wildfires, two of which caused major damage to Berkeley and Oakland. (See 1923 Berkeley Fire and 1991 Oakland firestorm).