def get_nkn_url(variable:str, year:int) -> str:
    """
    Constructs URL to download data from University of Idaho (UI)
    Northwest Knowledge Network
    given a year and a band

    :param year: year
    :param variable: Gridmet band (variable)
    :return: URL for download
    """

    base = "https://www.northwestknowledge.net/metdata/data/"
    pattern = base + "{}_{:d}.nc"
    return pattern.format(variable, year)