In January, on average three out of four days are below freezing () and one out of four days is colder than  (1961-90). The coldest temperature recorded is , on 21 January 1841, while the coldest recorded at Blindern is  in January 1941. The coldest month on record is January 1941 and also January 1947 with mean  and average daily low . The average date for the first overnight freeze (below ) in autumn is 17 October (1981-2010 average for Oslo-Blindern). Oslo sits right on the border between hardiness zones 7a and 7b.