It rains frequently, but not very hard

It rains here a lot; I can attest to that from my brief experience.  And Britain has a reputation for rain.  So I've wondered: how do these facts jive with the claim that Cambridge is the driest climate in Western Europe, north of the Pyrenees?

The answer is simple: while it rains frequently, it rarely rains very hard.

Looking at some collected weather information for Peterborough, UK (about 35 miles from Cambridge), the average number of "wet days" per month is nearly 14 in Cambridge (with a maximum of nearly 17 for January), but the average accumulation per wet day is a mere 3.4mm.  To contrast, consider data for College Park, MD, USA (where the University of Maryland is located).  Here, the average number of wet days per month is just over 9 (maximum 11), but the accumulation per wet day 9.7mm.  (I computed these numbers from the data in the table at the bottom of the above-linked pages, final two rows of the table.)

Over the course of the year, there is 556mm of rainfall in Peterborough, and nearly twice as much in College Park, at 1060mm, compared to 165 wet days for Cambridge vs. 111 wet days for College Park.

So there you have it: dry climate (low accumulation), but with frequent rain (many wet days).

I would like to find data about the number of overcast days in Cambridge, even those when it's not raining.  I'd bet the contrast here compared to College Park would be even more stark.

Thanks to Peter Sewell for the "wet days" data, and the initial bold claim about dry climate!