Taking a few minutes to learn the difference between weather proof and waterproof will save you from quickly discovering the difference at an inopportune time! Fortunately, there are specifications and guidelines in place that lets you know in no uncertain terms how your electronic device will stand up in a rainstorm or if you drop it in the toilet (which happens more than you might think).
According to the Merriam-Webster dictionary, something is weatherproof when it is "not able to be changed or damaged by the effects of the sun, wind, rain, etc." As far as clothing is concerned, weatherproof and waterproof are basically the same, although weatherproof boots, for example, tend to be warmer for wearing in the snow. However, for electronics and in particular walkie-talkies, a waterproof two-way radio is very specific, and it must adhere to rigid specifications.
JIS Standards for Water Resistance
The Japan Industrial Standards (JIS) for resistance to water uses a 0 to 8 scale to indicate the level of water ingress of a particular product (how easily water can enter). This is indicated on the product's specification sheet. A JIS rating of "0" means that there is no protection, whereas a rating of "8" means that the equipment can be continually submersed in water. The various levels include drip resistant, rain resistant, splash resistant, jet resistant, water tight and immersion resistant.
International Protection Rating (IP Code)
Business two-way radios frequently use the IP code to indicate the level of resistance to liquids and solid materials such as dust. In the radio's product specifications, you might see an IP rating of IP54. The first number is the level of solids resistance, and the number "5" on the 0 to 6 listing means that while the device is not entirely dust proof, it is dust resistant to the point that it will not interfere with the equipment's operation. The number "6" indicates no ingress of dust. The second number addresses water resistance. The number "4" corresponds to protection against water splash against the enclosure from any direction. As with the JIS ratings, "0" means not protected, while "8" means that the device can be submersed in water without any harmful effects.