The term "rain" pattern refers to a camouflage design that incorporates a heavy percentage of vertically-aligned "straits" or "flecks" which suggest an image of falling rain. During the Second World War, the German Wehrmacht utilized this feature on several camouflage patterns, primarily the Splittermuster (splinter) and Sumpfmuster (marsh) designs. These patterns were later modified and reproduced by the West German Bundeswehr and Border Guards, but the "falling rain" concept - in which the rain straits themselves were isolated as the major feature on a solid color background - emerged out of the Warsaw Pact countries of Eastern Europe. During the 1960s and 1970s when revolutionary movements were most active in Africa, some of these patterns also ended up in the hands of various insurgent organizations. The South African government even reproduced the pattern for its special forces units, where the pattern earned the nickname "rice fleck."
- Poland appears to have been the first Warsaw Pact nation to produce a simplified "rain pattern" design, consisting of thin brown rain straits on a field grey background. This pattern in turn later influenced the other Warsaw Pact designs.
- In 1963, the Czechoslovakia produced its own version of the "rain pattern" with very prominent rain straits over a subtle water-stain underprint, called oblacky.
- East Germany introduced its own "rain pattern" camouflage, called Strichmuster (line pattern) in 1965, and continued to issue the pattern until 1990.
- Bulgaria has issued several camouflage designs with the "rain" feature, including the early "frogskin" design and its own plain version based on the original Polish "rain" pattern. The former, although not truly a "rain" pattern because of its mottled underpattern, may still be categorized here.