Investigations conducted early in the twentieth century found that offshore waters of Atlantic Canada, particularly the Grand Banks, were among the foggiest regions on earth with fog being most prevalent from May to September, inclusive. Coastal and marine data collected in this region during past decades have been used to produce publications including atlases and climatological publications such as thirty year normals. Most recent normals, calculated using 1971-2000 data, are readily available online and continue to show high frequencies of fog during the summer months at coastal stations.

Further investigation is conducted by analyzing data from a few stations near the Atlantic coast of Nova Scotia. Visibility data for the period of record for each station, approximately fifty years, are used to determine fog occurrences for each year and month revealing both annual and monthly trends. Parameters, including sea surface temperature, air temperature, relative humidity and wind velocity, are examined to determine correlations with trends found in visibility data. Sea surface temperature data are acquired from offshore buoys plus other sources. Upper air data, available in the area for approximately the past fifty years, provide a means for detecting temperature inversions and very high relative humidity exposing the vertical extent of fog.

More recently, wind profiler data have become available on the southwest coast of Nova Scotia providing data in the boundary layer with enhanced temporal and spatial resolution at a point. These data are used to display greater vertical detail during recent fog events.