At a glance the NAONAO The North Atlantic Oscillation (NAO) is a weather phenomenon over the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea level (SLP) between the Icelandic Low and the Azores High. Through fluctuations in the strength of the Icelandic Low and the Azores High, it controls the strength and direction of westerly winds and location of storm tracks across the North Atlantic. over the last six months correlates well with daily mean CETCET Central England Temperature values, but UKPUKP UKP is a gridded datasets of UK regional precipitation. daily rainfall seems to have been higher when the NAO was negative. I Had to find another source to access the data, the file had disappeared from the UCAR site for some reason.