Starts fine when it’s dry out but doesn’t want to start when it’s wet & drizzly (btw: in Seattle, wet & drizzly is our winter thing). The engine spins fine & fast for as long as the battery holds out but doesn’t “catch”. If it does happen to start (usually but using the flooded engine, hold the gas pedal floored while cranking maneuver from the owner’s manual), it runs rough & try’s to stall requiring constant gas pedal management until it warms all the way up & then it’s fine.
I suspect it is due to old ignition wires.
“Purebred’s” suggestion is always a good place to start if the wires are old. Even if the wires are not the culprit, they are a maintenance item with a shorter life. That is, it is good prophylactic medicine. (Jokes, please…)
Before you replace them, try to start your car on a cold, rainy night while someone is looking under the hood at the ignition items. Sparks can sometimes be seen, which help diagnose the problem.
I’m going to go a different direction and say you have a cracked distributor cap.
You might try wiping down both the inside and outside of the distributor cap with dielectric grease.
What can happen is that when an engine is shut off the warmth can attract moisture in the air and this can essentially kill the spark inside the cap. Moisture will accumulate inside the cap much like a window in a house can sweat on the inside.
Next time it won’t start in damp conditions pop the distributor cap loose and take a look inside for moisture.
If the plugs and wires are old then those should be replaced also.
Next time ir rains, spray your cap and wires with WD40 or silicone spray. If that lets it start, replace the cap and wires.