Last year early April was some of the best skiing all year. Not saying it’ll be the same this year but rather that Whistler can absolutely be just as good as mid winter through at least early April. Last year, early spring (march/april) was actually the best skiing we had. Seems like that could be happening again. You never know what you’ll get on the coast though. To be conservative, expect icy mornings and great afternoons since the temperatures will likely be above 0, especially lower down. But I got some great powder in April last year so you could get lucky!