Might want to start here :?
Also as you hover over each property, on right hand side, there should be a copy value, copy path and pin value in the debug window.
I'm not sure if the gauge dashboard doesn't like something other than msg.payload, but you can try.? On your gauge tab, you could probably bring that value path directly in with mustache notation.? Replace {{msg.payload}} with the path of the property you want to display.? ie {{msg.observations[0].metric.winChill}} and see if that works for you.? If that doesn't work for you, you can use a change node to set msg.payload to the value of one of those properties and then feed it into a gauge node.??

Kyle
AA0Z