def fetch_tmax(dbname, dt, bbox):
    """Downloads maximum temperature from NCEP Reanalysis."""
    url = "http://iridl.ldeo.columbia.edu/SOURCES/.NOAA/.NCEP-NCAR/.CDAS-1/.DAILY/.Diagnostic/.above_ground/.maximum/dods"
    varname = "temp"
    return url, varname, bbox, dt