def separate_hourly_vals(hourstring):
    """Separate individual hourly field means from the string containing all
    24 values in the WDC file. Called by wdc_parsefile.

    Args:
        hourstring (str): string containing the hourly magnetic field means
            parsed from a WDC file for a single day.

    Returns:
        hourly_vals_list (list):
            list containing the hourly field values.
    """
    n = 4
    hourly_vals_list = [hourstring[i:i+n] for i in range(0, len(hourstring),
                        n)]
    return hourly_vals_list