From GridLAB-D Wiki
Climate data is obtained from the National Renewable Energy Laboratory (NREL) NSRDB: National Solar Radiation Database page.
United States
GridLAB-D supports reading TMY2 or TMY3 formats. Sample TMY2 and TMY3 data for U.S. locations is available on the GridLAB-D repository at Climate module TMY repository. US Data files are named with a two digit state designation followed by the city name, e.g.,
OR-Astoria.tmy2
For most states and cities, a GLM file is also created to facilitate loading the TMY2. These files can be included in any GLM file:
#include "OR-Astoria.glm"
To use modern exports from the NREL NSRDB website, they must be exported in a TMY3-compatible CSV format, or converted to TMY2.
International
There is currently no standard for supporting international weather data.