The first question we get after a forecast turns grey is whether we should move everything. Almost always, the answer is no. An overcast sky is the largest, softest light source anyone could rent, and it is free.
Skin, shadows and squinting
Direct midday sun puts hard shadows under everybody’s eyes and makes half a group squint. Cloud cover removes both problems at once. Faces stay open, colour stays even across a whole line-up, and nothing has to be fixed afterwards.
Flat light, no squinting, nothing to repair later.
A grey sky is not a compromise. It is the light most portrait photographers would build if they could.
What cloud does cost you is drama — the long shadows and warm rim light of a clear evening. So we plan for both: the group frames early, when even light is worth more, and the two of you later, when a break in the weather can be used if it comes.