See this example:
Note that there are plenty of libs for parsing JSON files if you have them on disk already, e.g. this one. After add it to the path:
>> data=loadjson('4.5_month.geojson.json')
data =
struct with fields:
type: 'FeatureCollection'
metadata: [1×1 struct]
features: {1×389 cell}
bbox: [-179.9476 -61.7431 4.3800 179.4478 79.5651 614.2600]