Altadena weather
Loading live data…Latest for Altadena: NWS (National Blend (NBM)): 55° Clear · American (NOAA GFS): 58° Clear · European (ECMWF): 53° Clear.
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active National Weather Service watches, warnings and advisoriesChecking the National Weather Service for active alerts covering Altadena…
Altadena weather in numbers
measured normals and 10 years of recorded weatherAltadena swings 44°F across the year, from 89°F highs in July to 45°F lows in January, and February is usually the wettest month in a year that brings about 20 in of precipitation. Over 10 years of recorded weather it averages 165 days a year at 77°F or above, 87 of them at 86°F or above, 0 frost nights, and rain on 50 days.
Day counts are from the ERA5 reanalysis for Altadena’s grid square, 2016 to 2025, counted the same way for every city so the numbers compare. A reanalysis square is an area, not a weather station, so it is good for counting days and not for a single day’s record.
The weather map: all three models at once
NWS, American, European side by side around Altadena and nearby towns.Live rain radar →Altadena hourly forecast: next 14 hours
consensus of the three modelsRain in the next 24 hours, model by model
each model's own hourly precipitation, side by sideLoading the three models…
Altadena 10-day forecast, out to 14 days
where the models agree, and where they splitAltadena, California (CA) is at its warmest in Jul (average highs near 89°F) and coldest in Jan (lows around 45°F), with roughly 20 in of precipitation across the year. Below, compare what NWS, American, European forecast for Altadena right now, and see exactly where they disagree.
We grade every model against the weather that actually happened, so you can see which forecast model is most accurate in United States before you trust any single number.
Altadena climate by month
average daytime high and overnight low across a typical year (1991-2020)Source: 1991-2020 averages, ERA5 for this place adjusted with NASA POWER.
How the weather around Altadena has changed since 1995
Altadena sits in the same roughly 50 km square of NASA's reanalysis as Los Angeles. That square ran 1.1°F warmer in 2015-2024 than in 1995-2004. See the full 30-year picture on the Los Angeles page.
Which forecast is most accurate in Altadena?
CheckWeather Score, graded against the weather that actually happened
The CheckWeather Score blends temperature, wind and rain accuracy, each measured against ERA5 (the recorded weather) over the last 30 days across 1999 cities. Lower error means a higher score. See which forecast model is most accurate in United States, how we measure forecast accuracy, or which model each weather app uses.
What do you think of the forecasts?
your vote countsThe accuracy above is the measured record. This is your opinion: which forecast service do you trust most in United States? Give each 1 to 5 stars.
One vote per service. Anonymous: we store no personal data, only a one-way hash of your connection for a day to stop double votes.