Most modern day backpacks are water resistant but not waterproof. They might keep their contents perfectly dry in a light shower but prolonged or heavy rain will eventually soak in (either through the material or through the zips) and your clothes, maps, and food will get damp. Nobody wants that- a wet jacket is no use if it gets cold and a wet sleeping bag is one of the worst things a hiker could hope to avoid. Happily, rain covers for backpacks are lightweight, adaptable to a wide range of different bag styles, and simple to deploy even in the worst weather.
Osprey Packs Ultra-light Raincover - X Small 232103
Osprey Packs Poco Sun Shade 233110
Osprey Packs Hi-Vis Raincover - XSmall 233010
Equinox Gila Ul Horizontal Pack Pocket LIBER145692
Equinox Ultralight Stingray Pack Cover 146212
Outdoor Research Large Sensor Dry Envelope 36006
Sealline Map Case - Small CASCA08703
Dakine Leather MP3 Case DKINE8160031
Sealline Map Case - Large CASCA08699
Cascade Designs eSeries Case 8 06490
Sealline Map Case - Medium 08701
Cascade Designs eSeries Case 8 06489
Equinox Mantaray Day Pack Cover 145740
This section is also home to a variety of handy accessories. There are pouches for cameras, cell phones, laptops and tablet computing devices (both padded and waterproof plastic), sun hoods for baby carriers, and a whole collection of gadgets and pouches to help outdoor folks organize the contents of their packs and make sure everything gets to the end of the trail in one piece.