In the winter months, the rain vs snow line can be one of the trickiest areas to forecast. This is the exact point where the temperature drops to freezing and rain turns to snow. One way meteorologists determine the rain vs snow line is by the 540 line. Wherever this line shows up on forecasting models, it’s an indication that anything north of this line will be snow and anything sound of the line will be rain. However, if you are located right along the line, just a few miles can mean the difference in whether you experience all rain or all snow.

Another rain vs. snow line can also be used when talking about elevation. During the winter months in mountainous regions, lower elevations will experience all rain, but once you drive into higher elevations the rain quickly turns into all snow because the temperature has dropped below freezing. It’s important that meteorologists can forecast this because people need to know at what elevation they will experience snow, so they can be prepared.

This can make travel very difficult. Travelers are urged to be ready for the changeover from rain to snow and stay vigilant.

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This segment originally appeared in today's edition of the Morning Brief newsletter. Sign up here to get weekday updates from The Weather Channel and our meteorologists.

J​ennifer Gray is a weather and climate writer for weather.com. She has been covering some of the world's biggest weather and climate stories for the last two decades.