Years missing: None
NAO - Negative
January
February
Years missing: None
March
April
Years missing: None
Years missing: None
May
June
Years missing: 1994, 1982, 1975
Years missing: None
July
August
Years missing: None
Years missing: None
September
October
Years missing: None
Years missing: 1993, 1975, 1952
November
December
Years missing: None
Years missing: None