Even if March officially heralds the beginning of spring, it can still be quite cold in Zurich and may even snow. With a bit of luck, the first sunny days bring with them temperatures of 10–15° C (50‒60 °F).
Be sure to pack: warm jacket, scarf and hat, but also lighter clothing for warmer days.
In April, anything is possible. The weather can change from rain to sunshine within a matter of hours. Rainstorms are not uncommon and it could still snow. Generally speaking, it is milder than the previous months, with the maximum temperature averaging 14° C (57 °F).