About the data
forecast.blue shows what the weather will do where you are, how sure that is, and what it means for your home. Here is where every number comes from and how to read it.
Sources
- Official forecast, hourly forecast and observations
- National Weather Service (NOAA)Shown as official and quoted word for word.
- Alerts
- National Weather ServiceAll active warnings, watches and advisories for your spot, checked every minute.
- Ranges and agreement
- Independent global and regional forecast models (US, European, German and Canadian centres)Compared to show how sure the forecast is.
- Ranges and agreement, days 1–15
- Google DeepMind WeatherNext 3, via Google BigQueryOne more model in the comparison, not a separate forecast. © 2024-5 Google LLC, whose machine learning models were used to create the experimental data made available under the following licence terms https://storage.googleapis.com/weathernext-public/terms-of-use.pdf. This data is intended for experimental modelling only and is not intended, validated, or approved for real world use.
- Climate normals and records
- NOAA normals and station records via the Regional Climate CentersAlways named by station and period of record.
- Air quality
- AirNow (U.S. EPA and partners)Real-time readings are preliminary; official EPA colours and categories.
- Days 17–30
- ECMWF EC46 extended-range ensemble, via Open-MeteoBased on data and products of the European Centre for Medium-Range Weather Forecasts (ECMWF), CC BY 4.0. We turn the ensemble mean and spread into a daily range. ECMWF accepts no liability for errors or omissions in the data.
- Radar
- NOAA MRMSWe render the mosaic ourselves.
- Sun and moon
- CalculatedStandard astronomical formulas; no outside service.
Reading a forecast here
Ranges. “High 58° (54–63°)” means 58° is the most likely high and it will very probably land between 54° and 63°. A wide range is the forecast being honest, not vague.
Agreement. Each day is labelled by how closely independent forecasts agree:
- Forecasts agree. Independent forecasts are close; the range is narrow.
- Mostly agree. Independent forecasts are fairly close; small surprises are possible.
- Forecasts differ. Independent forecasts disagree; expect changes and plan for the range.
- One forecast only. Only one forecast covers this day, so there is nothing to compare against.
Out to 30 days. Days 1–10 are the regular forecast. Days 11–16 show the range the models expect. Days 17–30 come from ECMWF’s EC46 ensemble: the middle of its runs and the range most of them fall in, next to the typical high and low for each date, with NOAA’s outlook for a warmer, colder, wetter or drier stretch. The further out, the more it tells you about the overall direction and the less about a single day.
Records. A record is the most extreme value at a named weather station over its period of record, never an estimate from a model grid.
Location and warnings
Your precise location is asked for only when you tap “Use my location”, and it is rounded to about a kilometre before it leaves your device. Your unit and theme choices stay in your browser.
Weather that can hurt you comes from the National Weather Service. If something here disagrees with an official warning, follow the warning, and see weather.gov (opens in a new tab).
Who runs forecast.blue
forecast.blue is published by DotBlue LLC (opens in a new tab), a UniCo Group (opens in a new tab) company. Colorado pages also show UniColorado Heating & Cooling (opens in a new tab), a Denver HVAC installer in the same group. Questions and corrections: contact.