To evolve eevee into umbreon does the happiness level have to reach max at night?

Question

can the max be reached at the day time and just level at night

Answer 1

Your Eevee can have max happiness at any time at all. However, it must gain a level at night in order to evolve into Umbreon.

Hope I helped. :)
Source: Myself x3

Answer 2

You can max its happiness at any time. However, it must then gain a level when it is night time to evolve into Umbreon.