The Collaborative International Dictionary of English v.0.48:

Summer \Sum"mer\, v. i. [imp. & p. p. Summered; p. pr. & vb.
   n. Summering.]
   To pass the summer; to spend the warm season; as, to summer
   in Switzerland.
   [1913 Webster]

         The fowls shall summer upon them.        --Isa. xviii.
                                                  6.
   [1913 Webster]