Floods, storm damage and hailstones the size of golf balls have landed RSA, the insurer behind More Than, with a £50m bill.
The insurer yesterday said the wettest June on record cost it £40m, and more rain looks like leading to a £10m hit in July as Britain keeps being battered.
It added that the East Midlands, the North-east and North-west were the worst-affected areas, with London relatively unscathed.
RSA, which operates in 140 countries, also said it expected losses related to two earthquakes in the Emilia-Romagna region of Italy in May to be about £35m.
The shares slipped 3 per cent on the news, though later recovered a little, to end up 0.6p at 108.9p.
Analysts noted that although the hit to the bottom line is bad, the claims from poor weather are still far short of the company's £120m bill from the widespread flood damage in 2007.
RSA said more than half its weather-related UK claims have already been settled.
The group's combined operating ratio, which shows claims and expenses as a percentage of premium income, where a figure below 100 per cent means a profit is being made, has been affected by the recent claim losses. RSA said it is now expected to be "better than" 96 per cent, against 95 per cent previously.
RSA, which employs 23,000 staff, has major operations in Canada, Ireland and Scandinavia, as well as across Asia and Latin America.