Rain gear is a frequency decision

Rain is possible almost everywhere, so possibility is a useless packing criterion. The useful questions are how often it falls and how long each episode lasts.

Frequent light rain and rare heavy rain need different answers

A climate with persistent drizzle demands a garment worn for hours at a time, which makes breathability and fit more important than absolute waterproofing.

A climate with short intense downpours demands something that can be deployed in seconds and put away wet, which favours packability over comfort.

Carrying the wrong one is the common error: a heavy shell for a place where the rain lasts twenty minutes, or a thin layer where it rains all day.

Waterproof and breathable are in tension

A fully waterproof fabric blocks water in both directions, so perspiration condenses inside. In warm conditions the wearer ends up wet regardless of the rain.

Breathable membranes let vapour escape while blocking liquid, which works within a limited range of temperature and exertion and less well outside it.

Ventilation openings under the arms and at the front do more for comfort than a higher fabric rating, because they move air rather than relying on the membrane.

An umbrella is a different tool

In a city, an umbrella keeps a whole outfit dry without being worn, which suits walking between indoor places rather than being outdoors continuously.

It fails in wind and occupies a hand, so it is poor for hiking, for carrying luggage, and in exposed coastal places where the rain arrives horizontally.

Its other advantage is that it is disposable in a sense a jacket is not. One bought locally at the start of a wet week can be abandoned at the end of it.

Shoes decide how the day recovers

Wet outerwear dries overnight on a hanger. Wet shoes frequently do not, which means one rainy afternoon can affect the following two days.

The practical protection is a second pair, or footwear that tolerates water and dries fast, rather than a waterproof shoe that holds water once it has entered over the top.

Synthetic uppers and thin socks dry overnight in a heated room; leather and thick wool do not, which makes the material a scheduling decision as much as a comfort one.

The bag needs covering too

A rucksack absorbs a surprising amount of water and passes it to the contents. A cover or a liner sack is lighter and cheaper than replacing what it protects.

Electronics and documents are the items where the failure is expensive, so a sealed bag inside the pack does more useful work than treating the outside of it.