>>625237>military surplus for a good hiking jacket that will stand up to water.There is "water PROOF" and then there is "water RESISTANT".
Goretex or similar materials (or an oldy timey rubberized rain coat) are water proof and you will not get wet.
While milsurp jackets are pretty sturdy, they are usually just water resistant (as are most commercial /out/ jackets) and even if you blast it with ScotchGuard, you'll eventually get wet in a steady rain or heavy downpour.
If you expect to be outdoors with no shelter and might get caught in the rain, you really ought to have a Goretex or similar waterPROOF and breathable jacket/coat.