I love this (presumably automatic) characterization from:
"A lot of rain (rainy season) falls in the months: January, February, March, April, May, June, July, August, September, October, November and December."
Yeah, sounds about right.
I mean it rains a bit but reputation for rain is far in excess of the reality if you were to compare it with many north American cities.
Have a look at http://www.worldclimate.com/ to compare. London is pretty dry.
In London, rain is much lighter, but much more frequent and much less predictable. So carrying an umbrella is a must.
I forgot this on my last trip to London. It was sunny when I got on the underground at Heathrow. By the time I got to central London, it was pouring, and I was soaked by the time I had walked to the office.
Coats, hats, and hoodies are much more common than are umbrellas, unless it's raining cats and dogs.