Just realized I missed the original question. My apologies. I am a bit further south than you but it can be a crap shoot here as well. In late April, early May you might start the day in a light jacket and shorts or you might start in tights, a balaclava and heavy jacket and either way you could be stripped down to a sleeveless jersey and shorts by noon. You would need to be prepared for anything and be able to pack it with you as you take it off.