Most countries in Europe have summer time since 31st March.
United Kingdom
GMT (Greenwich Mean Time) = winter time (GMT + 0)
BST (British Summer Time) = summer time (GMT +1)
WET (Western European Time) = winter time (GMT +0)
WEST (Western European Summer Time) = summer time (GMT +1)
France and most countries of the European Union
CET (Central European Time) = winter time (GMT +1)
CEST (Central European Summer Time) = Summer time (GMT +2)
See also:
https://en.wikipedia.org/wiki/Western_European_Timehttps://en.wikipedia.org/wiki/Central_European_Time