I suspect both of these (and other weather / meterological visualisers) draw on the same data sources. Nullschool lists its sources on the "about" page. Weath

I suspect both of these (and other weather / meterological visualisers) draw on the same data sources. Nullschool lists its sources on the "about" page. Weather data generally come from GFS (Global Forecast System): EMC / NCEP / NWS / NOAA.