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Clothing for shoulder monthes between Winter and Summer, or mixed conditions - cold water but medium to warm air temperature, etc.
Before you rely too heavily on these styles for warmth you should test them in the conditions you intend to use them in. Farmer Johns/Janes can be deceptive - providing a fair amount of warmth while you are dry, but providing surprisingly little protection when wet or submerged - often the long zippers, etc. simply allow too much rapid water entry and exit to slow heat loss.