Does 100% Humidity Mean It'll Rain?

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By By Steve Pool

SEATTLE - When the relative humidity reaches 100 percent, you'll notice it'll feel quite wet outside, but that doesn't necessarily mean it has to rain.

One-hundred percent humidity means the air is completely saturated and is holding its maximum amount of water vapor. That will make it appear foggy outside with perhaps some drizzle or mist.

But the air doesn't have to be fully saturated to have rainfall. When it's raining, it just means the raindrops have become heavy enough to where they're heavier than the surrounding air, but that doesn't mean the air has to be completely saturated. A majority of the time when it's raining, the humidity is less than 100 percent -- likely between 60 and 100 percent.

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