|The staff at the Alaska State Climate Center is happy to help you with your climate data requests. Before contacting us with your data requests however, we suggest that you browse the page below to see if what you are looking for is perhaps just a few mouse clicks away. If it is not, or you require some assistance, then please visit the "Contact Us" section at the bottom of the page.|
Obtaining climate data from NCDC
- Obtaining particular products from NCDC
- About LCDs
- COOP data
- Other data from NCDC
- Contact us for more help
Most of the data used in fulfilling data requests comes from the National Climatic Data Center (NCDC). NCDC is the branch of the National Atmospheric and Oceanic Administration (NOAA) charged with archiving climate data gathered by the National Weather Service (NWS), the National Ocean Service (NOS), and a host of other agencies. NCDC is typically the first "go-to" site for climate data.
The base address link for most of the climate products that people are seeking from NCDC (until NCDC changes it!) their "Most Popular Products Page" is: http://www.ncdc.noaa.gov/oa/mpp.
Obtaining particular data products from NCDC
Two of the products we are asked for most are the "CD" (Climatological Data) and "LCD" (Local Climatological Data) products from NCDC. Online access is free for .gov, .edu, .mil, .k12, .us and other selected domains. Typical charges to the general public are about 3-4$ per download.
The CD document is state specific and is the most comprehensive document in terms of number of observing sites, with hundreds of locations for each state listed. Actually, a separate CD is issued for each state by month, as well as an annual summary for each state). The CD is the main public dissemination form for data derived from the NSW Cooperative Observer Program (COOP). (For an overview of COOP sites in Alaska go here.) The documents are in .pdf format
Examples are given here for both monthly and annual Alaska CDs:
| Alaska CD 05/2010|| Alaska CD - Annual|
The monthly CD (about 36 pg.) is presented in a daily summary format, with the high and low temperatures listed for the 24-hour observing period (°F), the measured liquid-equivalent precipitation, inches of snow fall in the observing, and, in most cases, the accumulated inches of snow on the ground. A monthly summary for each station is also included, which has various climatological data of interest, like heating and cooling degree days (HDD and CDD), precipitation totals and the like. Note that CDs never contain wind data. For that you need an "LCD" or "QCLCD" (see below), but these are available for only a subset of stations found in the CD.
One of the oddities of the CD document is that it is arranged first by climate division (Cook Inlet, South Coast, Bristol Bay, etc.) and then by alphabetical order within that division. This can make finding a particular station difficult if you do not know its climate division. Fortunately. the text of the CD in electronic .pdf file can be searched by most modern PDF browsers (e.g. Adobe Reader, http://www.adobe.com) so you can search for the station you are interested in.
The annual CD publication (about 44 pg.) provides data for the calendar year, summarized yearly and by month (no daily data) and includes comparisons with climatological "normal" values. The annual CD also has a table of sites listed alphabetically. This is a handy way to find out both the climate division that a site is in, and other data such as longitude, latitude, and elevation.
To obtain CDs from the NCDC web site go here.
As the name "Local Climate Data" suggests, various flavors of LCD documents (LCD, QCLCD, ULCD) give the monthly summary of the observations for a single station and contain a more comprehensive data set, often with some form of wind data. Depending on the variant of the LCD the down-loadable document comes in tabular form (printable web table), PDf document form (.pdf file) or ascii form (plain text) or sometimes a combination of these.
Most of the data in the CD are derived from an Automated Weather Observing System (AWOS) or Automated Surface Observing System (ASOS), the automated weather observing platform deployed at many airports. (A heads-up, if the location you want data for does not have a nearby airport with an ASOS or AWOS, it is highly unlikely that an LCD will exist for that site.) From the LCD viewpoint, for the most part AWOS and ASOS data are interchangable. NCDC notes these differences:
# Some differences between ASOS and non-ASOS stations: ASOS: Elevation is available and will be displayed Fahrenheit temperature variables will be displayed in whole degrees. Celsius temperature variables will be displayed in tenths of degrees Non ASOS: Daily summary forms are not available Fahrenheit and Celsius variables will be displayed in whole degrees Sea Level Pressure and Total Precipitation values are not available Other elements/values will occasionally be unavailable
In some instances hourly observations are available as well, depending on the specific type of LCD one has selected. Below, the various flavors of the LCD the LCD, QCLCD and ULCD are discussed. Links for the various options can be found on the page: http://www.ncdc.noaa.gov/oa/mpp. Again, the section for the LCDs, "Most Requested A" as of this writing looks like this:
The regular "edited" LCD document comes in hardcopy (.pdf) form only. NCDC describes the LCD as:
A monthly summary from major airport weather stations that includes a daily account of temperature extremes, degree days, precipitation and winds. Also included are the hourly precipitation and abbreviated 3-hourly weather observations. An online annual subscription is available to these data which includes access to all back issues that are online.
This is probably your best bet for older data, even though NCDC states that they are still working on years earlier than 1995. Also the coverage is not as great as the QCLCD, which includes many smaller airports. (QCLCDs are only available for 2005 and later, however). Also note that if the location of the observation has changed significantly, the site of interest might appear under two or more sequential listings in the block of heading to choose from.
For example, in the above list snippet from the LCD menu, There are several instances of "ANC" data. Upon closer inspection, it is apparent that they span different time periods. In this case the official Anchorage observation site "ANC" has changed physical location on occasion; enough of a location change that the station received a new WBAN designator. So... if you need a long term record of LCDs, you might need to access several different observation sites, all called ANC.
In accessing the NCDC listing of records you will also encounter interesting sites with a relatively short-term record, for what ever reason. The ANCHORAGE PARK STRIP shown above is one of these. An annual edition also exists for each year, summarizing the data for the calendar year. An example of each, for Homer, AK is given below.
| edited LCD Homer, AK||edited LCD Homer, AK ANNUAL|
The existence of the edited LCD suggests that there might also be unedited LCDs as well. And there are: the ULCD. The caveats on the ULCD:
- they exist for the period only before 2005, typically back into the middle to late 1990s
- they are available as web (.html) documents or comma-delimited ascii (test) files only (no .pdf files)
- that they available for a much larger number of sites than the LCD
While no samples of the ULCD are available for download on this site, they are quite similar to those for the QCLCD which is discussed in the following section.
The final LCD category, the Quality-Controlled Local Climate Data (QCLCD) is available monthly for a large number of stations but, in contrast to the ULCD, the QCLCD is available only after Jan. 1, 2005. Besides the daily summary format similar to the LCD, a variety of other items are available.
- Hourly observations (a long list for a whole month).
- Hourly precipitation is also available hourly at most observing sites.
- the remarks section of each hour's observation are also available. These can be hard to interpret, but some hours may contain useful information, depending upon what you are looking for.
Similar to the ULCD, the QCLCD is not available in hard copy (.pdf) format. Available data formats come in two flavors: .html (web page) and ascii (plain test) format. If html is your choice (much easier on the eyes, but not useful as numerical data), you can capture the data table from NCDC as it is displayed on your browser by saving the page in its .html form using some type of browser cammand such as (Firefox) :
File->Save Page As...
or print the screen directly for a hardcopy. (Note that you may have to change your printed page orientation to "landscape" for best results).
The other option is to get plain test format. This is what you want if you intend to use the data in a spreadsheet or some other program. This format is not easy on the eyes but, once captured, can be directly imported into most spreadsheet programs as CSV-formatted (comma-delimited) data.
It you request ascii data from NCDC, it will be dumped (unformatted) directly into your web browser. To save it, do something like:
paste it into your favorite text editor, and save as a file. (NOTE: Do not paste the data into a word processor like Microsoft Word, as you do not want the text formatted in any way).
Below is a matrix where you can download samples of data for most of the varieties mentioned here (as before, for Homer, Alaska)
|DAILY SUMMARY||HOURLY OBS||HOURLY REMARKS||HOURLY PRECIP|
|HTML||GET DATA||GET DATA||GET DATA||GET DATA|
|ASCII||GET DATA||GET DATA||NO DATA||NO DATA|
For information on how to navigate to the LCD download location go to the section About LCDs
NOTE: this data is free to all users.
Depending on your needs, one further source of data to consider from the NCDC download page is the COOP data. The nature of COOP data is touched on briefly in the CD section. The NCDC COOP data download page (currently found at http://www7.ncdc.noaa.gov/IPS/coop/coop.html) says the following of COOP data:
A monthly log that includes a daily account of temperature extremes (participating locations) & precipitation, snow, and snow depth. Available for thousands of sites which are a part of the cooperative observing network in the US. This data has a lag time of 2-3 months.
The .pdf document you download is actually a scanned copy of the actual "B91" form that the observer filled in by hand, so the legibility varies depending on the observer's handwriting. One nice thing about having the actual form is that the observer often includes useful comments in the Remarks section. For an example of the data form see the .pdf file for Homer 8NW (8 miles northwest of Homer).
| Homer 8NW|
NCDC notes that they are in the process of converting the B91s to a digital form, so it is hard to know whether you will get a scanned or digital form until you download it.
Other Data From NCDC
While adequate for about 90% of our data requests, the products discussed above just scratch the surface of what is available (either free or for a fee) from NCDC. If you don't see what you want above, we suggest you spend a few minutes browsing the full holdings of NCDC web site from the NCDC HOMEPAGE.
Another great source for more specialized data is our Climate Links page, with links to a great many Alaska weather and climate data sources. And, of course, feel free to contact the staff of the Alaska State Climate Center. Often we can point you directly you to the type of data you are seeking.
Contact Us for More Help
Can't find what you are looking for? Need some help interpreting the data? Not sure what kind of data you need? Go to our CONTACT US page for information on how to contact ASCC staff. We are glad to help you.
THE FINE PRINT
The data sources listed on this website are provided as a service to our clients. Their listing on no way implies an endorsement of their services or quality and/or validity of their data. The National Climatic Data Center (NCDC) is the only provider of data that is certifiable. In many cases, the agencies and data providers listed herein are not the initial or primary collectors of the data and are not responsible for the provenance of the data they provide.
This web site is by no means intended to be an exhaustive collection of Alaska climate data. If you are aware of a provider of Alaska climate data, private or public, that you feel should be mentioned this site, please Contact Us with the pertinent information and we will include it in our offerings.