FAQ - Forecasts
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We provide a five to seven day forecast on our website. To find this information, just enter your city name or zip code into the forecast search box near the top of the page.
Five Day vs. Extended
The 5-day forecasts are specifically for one zip code. In other words, they are the temperatures you should see for highs and lows for your zipcode.
The extended forecasts below the 5-day forecasts are for larger areas (specifically, National Weather Service forecast zones). The National Weather Service chooses to name one temperature instead of a range of temperatures when they forecast for your entire county.
The times in our current conditions, both in our weather stickers and in other features on our website, are those for the National Weather Service official weather observation sites. These sites are nearly always located at airports and are updated once per hour, typically, at about five minutes before the top of the hour. When interesting weather is occurring at the airport these observations may be updated more frequently. When there are delays in reporting weather data, the data on our website may also be delayed. Some NWS stations report in different increments and at different times.
At Weather Underground, we do our very best to ensure that our data is up-to-date; however, please remember that we rely on external sources for information that may affect our website and services.
Coordinated Universal Time or Universal Time Coordinated (UTC): A coordinated time scale, maintained by the Bureau International des Poids et Mesures (BIPM), which forms the basis of a coordinated dissemination of standard frequencies and time signals. UTC is roughly the same as GMT, Greenwich Mean Time. UTC and GMT are 5 hours ahead of Eastern Standard Time. If you haven't set your timezone yet, then the maps may appear in UTC. Click on [change timezone] to select the default timezone that you want maps and other things to appear in.
On our site, Travel Planner will give you a long range forecast based on past year's data. You can find this feature in the Feature bar at the top of our pages in the "Travel & Activities" drop down menu.
Other Sources of Long-Range Data
- For U.S. seasonal forecasts - go to: http://www.cpc.ncep.noaa.gov/
- The International Research Institute for Climate Prediction has long range forecasts for the whole world:
- For El Nino and La Nina info - go to: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml
Weather forecast graphs
The Weather forecast graphs on our site are produced from statistical forecasts made by the National Weather Service. You can find more information on how they are generated here:
Since these forecasts are automatically generated by computers, there is no quality check before the information is shown to you. Usually, before a forecast is made, meteorologists look at all computer weather forecasts to make a final decision on what will happen. This is because many times, an individual forecast model can be significantly off in its prediction. We put the Forecast Weather Graph product on the web site because we think it can help give detail to the forecast for the next few days. Yes, it can be wrong, but in the long run, we think it helps more than it confuses.
Chance of Storm/Precipitation
The terms simply translate to a percentage. Following the terminology used by the National Weather Service, 10 percent probability means isolated; 20 percent chance is widely scattered; 30 to 50 percent chance is scattered; 60 percent and higher is likely.
Wind direction tells us the direction FROM which the wind is blowing. So, a north wind is blowing from the north, and a south wind is blowing from the south (toward the north). If the wind is turning toward the south, the wind is beginning to blow from south to north.
Click on the link "Forecast Weather Graph (NGM/MOS)" at the bottom of the forecast page to get the detailed wind forecast (only ahead 48 hours). Some National Weather Service offices don't offer wind forecasts in the regular worded forecasts. Past 48 hours, reliably forecasting the wind direction and speed is usually extremely difficult, so the National Weather Service doesn't do it.
Air Pollution Forecast
We provide data where it is available in the US. Look at the "Air Pollution Forecast" section of a forecast weather page to find air quality information and links to details related to the data.
For more information about air quality, please visit the following page:
The EPA has a great web site with more information at:
All the pressure information in the "Current Conditions" section of our web site is sea level pressure. This means that the pressure is corrected to sea level. As a result, elevation should have little or no effect on the pressure readings.