Weather is being, well, weather. Even with tools like very powerful computers, complex algorithms, radars and satellites, IMHO weather prediction is still an art. You can predict weather with approximately the same accuracy as trained and educated meteorologists equipped with the latest equipment when it comes to a period of 24-48 hour ahead.
Regarding the status of car cleanliness. If your car is outdoor most of the time (a daily driver or is parked outdoor), there is no use to keep it clean in this weather pattern unless you live in an area currently having a drought. The ugly grime coating may act as a paint protection anyway (tree saps and animal droppings may need semi-immediate attention) and, with every washing, there is a chance of introducing new scratches. So, I say, in most cases, leave it alone. The only things needed periodic cleaning are the wheels to keep brake dust deposit from turning permanent; the cleaning period could be quite long depending on the type of brake pads. Add exhaust tips if soot deposit accumulated fast.
Relax
