Hi Paul,
You can create your on weather file in the SAM CSV format with any data you like. For example, you could combine solar resource data from one source with meteorological data from another source.
The SAM CSV format is described in SAM's Help system: You can find the description in the "Weather File Formats" chapter, or in the document listed at
sam.nrel.gov/weather-data/weather-data-publications.html.
Best regards,
Paul.