snprintf doesn't display float values
The standard avr-libc does not have float support enabled in the printf family of functions. This is because float support would bloat your code massively, and most people don't need it.
It is possible to enable it through some black magic (I don't know what, but someone else may), but in general you don't want to since there are better ways.
Typically you would use dtostrf() to format your float into a char array separately. Or if all you are doing is printing to serial then you wouldn't even format it into a string in the first place.
Serial.print(F(&quot;Temp = &quot;));
Serial.print(temp);
Serial.print(F(&quot;  Humidity = &quot;));
Serial.println(humid);