How the English Were Fooled by Geography

In the Age of Exploration sailors could establish their latitude (ie. how much north or south of the equator they were).  So English sailors knew the latitude of London was 51 degrees north.  Naturally when they first visited what they'd call New England, they figured that since the latitude was 41 degrees, or about 700 miles south of London, the weather should be warmer.  But Bartholomew Gosnold writes his father:

it is the latitude of 41 degrees, and one third part; which albeit it be so much to the southward, yet it is more cold than those parts of Europe, which are situated under the same parallel: but one thing is worth the noting, that notwithstanding the place is not so much subject to cold as England is, yet did we find the spring to be later there, than it is with us here, by almost a month: this whether it happened accidentally this last spring to be so, or whether it be so of course, I am not very certain; the latter seems most likely, whereof also there may be given some sufficient reason, which now I omit; as for the acorns we saw gathered on heaps, they were of the last year, but doubtless their summer continues longer than ours.

 Of course he was wrong--the New England summer is shorter and hotter.  Because the Gulf Stream had not yet been discovered as a thing affecting climate, Gosnold was fooled by geography and logic: similar latitudes should have similar climates.  According to my logic, this ignorance probably meant colonizing expeditions were less well prepared than they would have been if climate had been understood.