Out of topic. Lol..

Jerelly • A 24 years old newly wed wife.
Hello i know this is so out of topic. But i would like to know how cold it may get in Europe expecially swiss jungfrau? I will be going to europe 27 April for 18 days. Can i just wear inner turtleneck,  a cardigan or jacket for city like london and italy? And inner, cardigan plus a coat for jungfrau swiss? Is it enough? If i want to wear a maxi dress for inner, then jacket. Would it be okay too? ( ppl from europe country please comment if can ) thank you :)