National Weather Service United States Department of Commerce

NOAA Online Weather Data (NOWData)

Frequently Asked Questions

For more information on NOWData, see the Facts Sheet available here (pdf).

Data Availability

Are the data in NOWData considered 'official' for legal and other such purposes?

No. NOWData provides up-to-date information based on archived AND preliminary data holdings by NOAA. For official data, you should contact NOAA’s National Centers for Environmental Information (NCEI) or the Regional Climate Centers. NCEI provide official certification for data being used in U.S. courts.

I noticed that the most recent data does not match data that I found of the NCEI web site. Why is that?

Preliminary data can be different from NCEI official data for a number of reasons related to quality assurance and processing schedules, as well as synchronization of the NCEI and ACIS databases. Ultimately, when processing is completed, the two data files will match.

Is it possible to download hourly/daily/monthly historical observations as far back as you have records for a station of interest?

Historical data can be obtained through the National Centers for Environmental Information or Regional Climate Centers. Links are found at the bottom of the NOWData pages.

I've been searching for weather data for my local station for some time now, and was thrilled to discover your "daily almanac" data. Do you have detailed data like that for the last several years?

Data beyond the timeframe presented in NOWData can be obtained from NOAA National Centers for Environmental Information or Regional Climate Centers. Links are found at the bottom of the NOWData pages.

I am conducting some research on past temperatures in location X. Where can I find daily temperature readings for the past 2 years? There is a place on your web site where I have found this criterion for the previous 2 months, but I need this information for a longer period.

NWS Forecast Offices archive preliminary climatology data for a minimum of 5 years at many locations. You can check to see if this information is available for you station of interest by choosing the tab marked 'Observed Weather' on the end opposite the 'NOWData' tab. Then choose 'Preliminary Climatology Data (CF6)' and see if your station is included. If the station is not available or if official data are required, you must contact the National Climatic Data Center or Regional Climate Centers. Links are found at the bottom of the NOWData pages.

Can you tell me what the wind speeds were for Hoodsport, WA on Feb 4th and 5th 2006?

For information, such as wind, that is not included in NOWData, you should contact the National Centers for Environmental Information Climate Services Division at (828) 271-4800.

Information on Instrument Standards and Computational Methods

Would it be possible to find out how you compute degree day data?

Daily degree days are simply based on the departure of the average of the maximum and minimum temperature from 65 degrees Fahrenheit. Monthly degree days are the sum of the dailies. Normals of degree days for monthlies are modeled. For more information, please go to:

I was wondering if the anemometer heights of weather stations were available online. If so, could you please let me know asap, thank you!

Wind measurements are generally limited to the airport locations, which have Automated Surface Observing System (ASOS) sensors. These sensors (anemometers) are deployed at around 10 meters.

I was wondering about the history of a station in terms of location and siting. Where can I find this information?

Check out NCEI's station locator at: or the Historical Observing Metadata Repository (HOMR) at NCEI at:

Missing Stations

Why is my local observing station not included in NOWData?

The list of stations provided in NOWData was developed through collaboration between the National Weather Service, the National Centers for Environmental Information, and the Regional Climate Centers. If you would like to see a station added to NOWData, you should submit a request to the climate focal point at your local Weather Forecast Office (WFO). An email link should be available through “Contact Us” on the left navigation bar of the WFO website.

Value Added Products and Services

I am in need of the forecast history each day. I know that this is provided for every city on a daily basis but I need this information on days that I do not have access to internet service. Do you have archived data available for all cities? Can you e-mail me the forecast for certain cities on the days that I am not at work?

Forecast histories are not available in NOWData. We suggest that you contact your State Climatologist to assist in setting up a script to handle routine forecast updates. A list of the State Climatologists is available at here.

Looking at daily data, some dates have an M or a &T in the field. What does this mean?

M stands for Missing. Data for an element will be missing if the primary sensor for that weather element is inoperable (e.g., has an outage) or malfunctioning (e.g., producing errant data) AND any collocated backup sensor is also inoperable or malfunctioning. T stand for Trace. This is a small amount of precipitation that will wet a raingage but is less than the 0.01 inch measuring limit.

NOWData is a project of the Regional Climate Centers, the National Centers for Environmental Information, and the National Weather Service.