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Weather extremes
How extreme does Castro Valley's weather get?
The hottest, coldest, wettest and snowiest days Castro Valley has recorded — the outer limits of what its weather can do, and how far they sit beyond a normal day.
The four kinds of extreme
The hottest, coldest, wettest and snowiest single days Castro Valley has recorded — each shown against what a normal day that time of year looks like.
That is about 31°F hotter than a normal September afternoon in Castro Valley (typical high near 77°F).
The three most extreme on record
About 43°F colder than a normal December night in Castro Valley (typical low near 43°F).
The three most extreme on record
More rain in a single day than Castro Valley usually gets in the whole month of December (typical December total about 3.2 in).
The three most extreme on record
How hot and cold it gets, month by month
The shaded band is the normal range of daily temperatures for each month. The dots show the most extreme it has ever been — so you can see how far beyond a normal day the records really sit.
Castro Valley's record heat sits well above even a hot day for the season — September's 108°F is about 31°F beyond a normal hot afternoon. Its record cold is just as far below a normal winter night — the dots mark how rare each extreme really is.
In plain terms
Methodology & sources
Temperature & precipitation — the official 1991–2020 climate normals from NOAA's U.S. Climate Normals, measured at Newark (NOAA GHCN station USC00046144), about 21 km from the city centre.