Weather in Alameda, month by month

Warmest month: September, 17.6
Coldest month: January, 9.4
Wettest month: December, 138 mm
Year: 2001-2020

Same data, same method, different place.

Your own numbers, worked out on the page.

Across the 2001-2020 normals, the warmest month in Alameda is September at 17.6 degrees and the coldest is January at 9.4, a swing of 8.2 degrees over the year. Those are monthly averages for the model cell the city sits in, not readings from a weather station in it.

Rain is heaviest in December, about 138 mm, and lightest in July at roughly 1 mm. Over a full year the cell above Alameda collects around 587 mm.

The months whose average sits between 15 and 24 degrees are June, July, August, September and October. That band is this page's own definition of mild and is stated so you can disagree with it rather than guess at it.

Humidity peaks in January at 84 percent, and the windiest month is May at 2.5 metres per second. Both are monthly means from the same twenty year series as the temperatures.

Rainfall is not spread evenly: 90 per cent of the year total falls in November, December, January, February, March and April.

Every figure here comes from one NASA POWER grid cell, at 37.77, -122.26, covering Alameda on the 2001-2020 climatology. One cell, one period and one provider for every month, which is what makes the twelve rows comparable with each other.

The source publishes a monthly mean and, separately, the highest and lowest values it recorded in twenty years. Those extremes are not a typical afternoon or a typical night, so nothing here is quoted as one. This page does not say what the daytime high usually is, because this source cannot say it.

Normals are not a forecast. They describe what twenty years averaged to, and any single year can sit well outside them. They also describe a model grid cell of roughly fifty kilometres rather than a weather station, so a coastal city and the sea beside it share one figure.