Figure 6. Variability in monthly mean sea levels from 1912 to 2011 at the Portland, ME tidal station; monthly averages for all data are shown in a solid red line. Note that generally, sea levels are slightly higher (~ 4 inches or 10 cm) during the summer months than the winter months, though winter months show much greater variability in terms of highs and lows. The figure also labels the highest average mean sea level values for each month; the two highest occurred in February and March, 2010. These were influenced by series of high water levels associated with northeast storms. The highest "summer" mean sea level values occurred in May 2005, June 2011, and June 2009. The May 2005 water levels were strongly influenced by a week-long series of northeaster storms, while the June 2009 and 2011 water levels were influenced by long periods of onshore winds and current anomalies. Data courtesy of NOAA's Tides & Currents website.
Last updated on April 30, 2012