Are wind chill and heat index mutually exclusive?

[sdennstaedt]

For the latest observations, can I assume that both of these values are mutually exclusive? That is, you can't have a value for both heatIndex and windChill. One will be null. Can they both be null?

"windChill": {
"value": null,
"unitCode": "unit:degC",
"qualityControl": "qc:V"
},
"heatIndex": {
"value": 37.114885778912878,
"unitCode": "unit:degC",
"qualityControl": "qc:V"

[StephenClouse]

Yes and yes.

Heat index is only valid when the real temperature is above 70F.
Wind chill is only valid between -50 and 50F.

The values will always be null outside of these temperatures.