Overcast: often the easiest portrait light
A bright cloudy sky behaves like a very large soft source. Skin is easier to expose, people are less likely to squint, and you can photograph in places that would be harsh at midday in direct sun.
Watch for dark eye sockets under very heavy cloud or deep tree cover. Turn the face toward the brighter part of the sky rather than simply increasing exposure.
Light rain: change the plan, not necessarily the date
Move closer to buildings, trees or a covered meeting point. Use shorter sequences and keep the camera bag organised so equipment is not left open. Wet paving can produce excellent reflections, particularly around the city and Grand Canal Dock.
For clients, bring a coat that can come off quickly, dry footwear and a simple umbrella if it suits the look.
Wind: the condition photographers underestimate
Wind affects hair, dresses, reflectors, light stands, microphones and comfort. On Howth, Portmarnock or Dún Laoghaire, a moderate inland forecast can feel much stronger at an exposed viewpoint.
If the session is about clean portraits rather than dramatic weather, moving inland to Phoenix Park, Malahide or a city garden can be a better decision than fighting the coast.
Strong sun: look for direction before power
Instead of putting a face directly toward strong sun, use open shade, turn the sun behind or to the side of the subject, and expose carefully for skin. Midday city portraits often improve immediately when you move one street or one tree line.
In summer, the easiest solution is often scheduling later rather than bringing more equipment.