def clean_temperature(v):
    """Clean the temperature variable

    Args:
        v (pd.Series): Series containing all temperature values

    Returns:
        v (pd.Series): Series containing all cleaned temperature values
    """
    # Convert values to float
    v = v.astype(float)

    # Extract indices of values to be converted from Fahrenheit to Celsius
    indices = v >= 70

    # Convert Fahrenheit to Celcius
    v.loc[indices] = (v[indices] - 32.0) * 5.0 / 9.0

    return v