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Weather extremes
How extreme does Altadena's weather get?
The hottest, coldest, wettest and snowiest days Altadena 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 Altadena has recorded — each shown against what a normal day that time of year looks like.
That is about 25°F hotter than a normal September afternoon in Altadena (typical high near 90°F).
The three most extreme on record
About 25°F colder than a normal March night in Altadena (typical low near 48°F).
The three most extreme on record
More rain in a single day than Altadena usually gets in the whole month of January (typical January total about 4.5 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.
Altadena's record heat sits well above even a hot day for the season — September's 115°F is about 25°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 Pasadena (NOAA GHCN station USC00046719), about 5 km from the city centre.