GWTC Forecasts

Download All GWTC Data (NOW UPDATED THROUGH 2021!)

Please note that this file is quite large (405MB) and thus had to be zipped (44MB). It still might take a little while to download. The codes for the weather types can be retreived in the table below.

The GWTC data in the file above are free to use for scientific research purposes only, with proper citation (Lee, 2014). The data will be updated annually, shortly after new data are posted on the NARR website (usually sometime in February). The data are organized with each row representing a day (with the dates listed in the leftmost row) and each column representing a grid point location (column headers are the first 4 lines: latitude, longitude, and unique x and y coordinates). Thus, row 5 begins the weather typing classification for each location on 1 January 1979 (note that the date codes are excel readable; so 28856 is 1 January 1979). Due to UTC time, the GWTC will not include December 31 of the most recent year, as data for part of this day of the year will only become available when next year's data are released. The table below shows the metadata in regards to what numbers represent what weather types.

Please just contact me ( with any specific data requests... I can easily provide:

I am also always interested in collaboration.

While the GWTC is available for all of North America, use of the GWTC in the tropics should be done with caution - as this region is subjected to very little variability. These data have also been regionalized, using the method described in Lee (2014), except with the entire spatial domain of 9027 points (region data).

This page will be updated to make it more user friendly as my web skills improve. However, for now, the best I can do is a single .csv file with all the data (above).

Metadata table:

11 Humid Cool HC
12 Humid H
13 Humid Warm HW
21 Cool C
22 Seasonal S
23 Warm W
31 Dry Cool DC
32 Dry D
33 Dry Warm DW
72 Cold Front Passage CFP
73 Warm Front Passage WFP


GWTC weather types for 1 January 1979.