Diamond Bar weather
Loading live data…Clear,much the same tomorrow
NWS, the American and the European model put Diamond Bar's high today between 73° and 78°, a 5° split. Tomorrow: clear, around 79°, with a 0% chance of rain.
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active National Weather Service watches, warnings and advisoriesChecking the National Weather Service for active alerts covering Diamond Bar…
Diamond Bar weather in numbers
measured normals and 10 years of recorded weatherDiamond Bar swings 51°F across the year, from 93°F highs in August to 42°F lows in December, and February is usually the wettest month in a year that brings about 21 in of precipitation. Over 10 years of recorded weather it averages 192 days a year at 77°F or above, 111 of them at 86°F or above, 0 frost nights, and rain on 44 days.
Day counts are from the ERA5 reanalysis for Diamond Bar’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 Diamond Bar and nearby towns.Live rain radar →Diamond Bar 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…
Diamond Bar 10-day forecast, out to 14 days
where the models agree, and where they splitDiamond Bar, California (CA) is at its warmest in Aug (average highs near 93°F) and coldest in Dec (lows around 42°F), with roughly 21 in of precipitation across the year. Below, compare what NWS, American, European forecast for Diamond Bar 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.
Diamond Bar 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 Diamond Bar has changed since 1995
Diamond Bar sits in the same roughly 50 km square of NASA's reanalysis as Riverside. That square ran 1.4°F warmer in 2015-2024 than in 1995-2004. See the full 30-year picture on the Riverside page.
Which forecast is most accurate in Diamond Bar?
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.
Where the models disagree
temperature and rain, judged separatelyThe models often agree on temperature and still split on rain, and rain is usually what decides whether a plan survives. A wide rain range means the shower is genuinely uncertain, not that the forecast is wrong.