One reservation might be that the years 1621-22 saw two consecutive 
bad harvest, declining money circulation, worsening trade and a 
general decline throughout England but was not associated with any 
war. Rather it spurned a big debate on economics... The Civil war 
(1642-49), which ends pretty much when the 'quiet' period you suggest 
starts, has not been associated with any particular long spell of bad 
weather to my knowledge. The War did lead to the death of one in ten 
men of a working age, ending in the commonwealth and Cromwell's 
protectorate/dictatorship which may account for why there is less 
domestic strife in the decade after Cromwell takes over...

Petty was, as I am sure you know, very concerned with the weather and 
its impact on land yields and national production. A lot of the data 
in his Political Arithmetick are derived from observations and 
assumptions about the weather conditions, although I don't recall him 
making any other connection with the weather.

Also, the notion that peace prevailed on the European continent for 
only one year out of the whole period 1551-1650 does not really 
surprise me very much. In fact, I doubt if you would find many 
hundred year spans, where the whole continent didn't host a war 
almost every year. The two 'Hundred Year wars' in France (1337-1453) 
and between France and England (1689- 1815) are pretty good examples 
of this, and that tendency has been pretty regular up until today. 
Going by Wikipedia 
(<http://en.wikipedia.org/wiki/List_of_conflicts_in_Europe>http://en.wikipedia.org/wiki/List_of_conflicts_in_Europe) 
there's been 24 theatres of war and conflict in Europe since 1989 
alone, some still ongoing... That's almost one per year on average. 
The chronological lists are far from complete, but they give a pretty 
good picture of a continent which celebrated the fact that No Army 
had crossed the Rhine for 60 years intent on warmongering in 2005. A 
real achievement in historical terms.

Best

Benjamin H. Mitra-Kahn