It seems to start blooming in November, shortly after the first rains and it continues until May (sometimes June).
It was one of the early colonizers after the Jesusita fire and one of the first things to bloom in the burned region.
There are actually two species of Marah in our area, this and M. macrocarpus which is supposed to be bigger in almost all ways. The simplistic way to distinguish them is to look at the flowers, flat flowers are this species, cup-shaped flowers are M. macrocarpus. That doesn’t work very well in SB where the two seem to hybridize. You can also brave the spines and open one of the fruits. If there are 4 seeds it is this species, for there are 8 or more M. macrocarpus.
Away from the coast and beyond Camino Cielo most plants I’ve seen look like this species, while further south there’s a confusing mix.