Climatic Research Unit : Data

North Atlantic Oscillation (NAO)


NAO data files : NAO visualisations : NAO values

Notes about these NAO index values:

  1. These values are all from the Jones/CRU NAO index (Gibraltar minus Iceland). This is most useful during the winter half of the year when Gibraltar and Iceland sea level pressures (SLP) are strongly anti-correlated and the NAO index measures a coherent pattern of stronger/weaker atmospheric flow into NW Euope. Results are also shown for the summer, but these should be interpreted carefully due to more complex circulation regimes in summer that may not be well-described by this NAO index, not least because Gibraltar SLP is influenced by the Iberian thermal low during summer months.
  2. The index was generated using a 1951-1980 reference period and therefore has a mean of zero during this period. It is inconvenient that this is a period of anomalous NAO index for most seasons, so the long-term mean of the index is not very close to zero when this reference period is used. See NAO visualisations to see a more representative baseline.
References:
Values : Recent : Ranked

Recent values

Monthly

Recent monthly NAO index values
YearJanFebMarAprMayJunJulAugSepOctNovDec
2009+0.60-1.43+0.15+1.74+1.52-3.05-0.92+1.07-0.63-1.53+1.68-3.73
2010-2.38-3.92-0.80-1.03-1.66-3.65+0.06-2.02-2.38-2.41-3.34-4.61
2011-1.38+2.79-0.17+2.39+1.08-1.58-3.39-2.41+2.97+1.31+0.74+3.20
2012+2.05+1.28+1.78-2.36-0.83-2.58-1.31-0.44-1.44-3.21-1.11+0.60
2013+1.08-0.26-3.74+0.03+1.23+1.40+2.52+2.16-0.57-0.36+0.04+3.54
2014+0.71+2.32+1.64+0.84-0.08-1.98+0.91-1.14-2.10+0.31-2.17+1.89
2015+2.81+1.47+1.99+1.03+2.09+0.28-2.15+1.47-1.65-1.13+3.54+4.22
2016+1.16+1.61+0.33-2.06-0.82-1.27+2.18+2.14+2.45-1.47-1.61+2.10
2017+0.17+1.38+1.05+1.50+0.38-0.55+0.10-0.04+1.42+1.36-0.90+1.00
2018+1.82-0.10-1.12+2.37+2.01-1.40+3.83+0.45-1.17-1.28
2019

Seasonal

Recent winter/cold season NAO index values
YearDJFDJFMONDJFM
2008-2009-0.47-0.31-0.42
2009-2010-3.34-2.71-1.78
2010-2011-1.06-0.84-1.52
2011-2012+2.18+2.08+1.73
2012-2013+0.47-0.58-1.11
2013-2014+2.19+2.05+1.31
2014-2015+2.06+2.04+1.05
2015-2016+2.33+1.83+1.62
2016-2017+1.22+1.17+0.27
2017-2018+0.91+0.40+0.34
2018-2019

Values :
Recent : Ranked

Ranked values

Highest monthly values

Ranked monthly NAO index (top 5)
YearJanYearFebYearMarYearAprYearMayYearJunYearJulYearAugYearSepYearOctYearNovYearDec
1983+4.821997+5.261903+4.051947+6.661823+4.651994+2.981857+5.361851+4.681865+3.241963+2.791913+4.622015+4.22
1890+4.321990+5.111994+3.681897+4.281956+4.541836+2.951836+4.331871+4.192011+2.971837+2.521992+4.521833+4.17
1925+4.231826+4.881882+3.611943+4.261964+2.511894+2.782018+3.831919+4.031923+2.641860+2.281881+4.341924+3.86
1993+3.911903+4.861830+3.581844+3.911922+2.361946+2.561969+3.691888+4.001854+2.621986+2.271978+3.911929+3.80
1916+3.821945+4.681948+3.481898+3.461937+2.311961+2.131876+3.481843+3.992004+2.511832+2.252015+3.542013+3.54

Lowest monthly values

Ranked monthly NAO index (bottom 5)
YearJanYearFebYearMarYearAprYearMayYearJunYearJulYearAugYearSepYearOctYearNovYearDec
1996-3.272010-3.921837-3.081831-3.151844-2.772010-3.651872-3.611956-3.151877-3.731842-3.731879-3.381976-3.63
1823-3.391986-4.021900-3.121971-3.151928-2.901891-3.741842-4.052007-3.411842-3.801922-3.951860-3.442009-3.73
1941-3.501853-4.042013-3.741822-3.191853-3.171824-3.941822-4.051870-3.412001-3.841993-4.131878-3.471853-4.28
1881-3.601895-4.141962-3.782000-3.341935-3.211997-4.051828-4.401827-3.561939-3.901926-4.161871-3.722010-4.61
1963-4.091947-4.601916-3.841929-3.802008-3.261842-4.301851-5.391999-3.671972-4.111864-6.051858-4.411996-4.70

Highest seasonal values

Ranked seasonal NAO index (top 10)
YearDJFYearDJFMYearONDJFM
1924-1925+3.351881-1882+3.161881-1882+2.49
1833-1834+3.301902-1903+2.871902-1903+1.88
1868-1869+3.051988-1989+2.861833-1834+1.82
1881-1882+3.011833-1834+2.821912-1913+1.73
1988-1989+3.001841-1842+2.592011-2012+1.73
1994-1995+2.891919-1920+2.541862-1863+1.71
1858-1859+2.701994-1995+2.441982-1983+1.67
1838-1839+2.661858-1859+2.401841-1842+1.66
1848-1849+2.581989-1990+2.371883-1884+1.66
1902-1903+2.471862-1863+2.252015-2016+1.62

Lowest seasonal values

Ranked seasonal NAO index (bottom 10)
YearDJFYearDJFMYearONDJFM
1826-1827-1.591887-1888-1.291955-1956-1.28
1935-1936-1.681880-1881-1.301842-1843-1.28
1976-1977-1.901855-1856-1.321864-1865-1.35
1894-1895-1.941978-1979-1.341878-1879-1.36
1978-1979-1.971894-1895-1.521855-1856-1.46
1916-1917-2.161935-1936-1.532010-2011-1.52
1968-1969-2.181916-1917-1.671887-1888-1.59
1962-1963-2.221968-1969-2.091968-1969-1.72
1995-1996-2.241995-1996-2.322009-2010-1.78
2009-2010-3.342009-2010-2.711995-1996-1.80

References


Last updated: October 2017, Tim Osborn

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Please use the attribution Climatic Research Unit, University of East Anglia