What is the lowest minimum temperature recorded in store 16 on January 2012?
lowest minimum temperature refers to Min(tmin); store 16 refers to store_nbr = 16; on January 2012 refers to Substring (date, 1, 7) = '2012-01'
SELECT MIN(tmin) FROM weather AS T1 INNER JOIN relation AS T2 ON T1.station_nbr = T2.station_nbr WHERE T2.store_nbr = 16 AND T1.`date` LIKE '%2012-01%'