def _calculate_full_regression(temp: float, rh: float) -> float:
    """
    Full heat index regression, applicable when HI from simple regression is over 80
    """
    return -42.379 + (2.04901523 * temp) + (10.14333127 * rh) \
           - (.22475541 * temp * rh) - (.00683783 * temp * temp) - (.05481717 * rh * rh) \
           + (.00122874 * temp * temp * rh) + (.00085282 * temp * rh * rh) - (.00000199 * temp * temp * rh * rh)