The Temperature Range of Rainfall

The Temperature Range of Rainfall If youve ever wondered why getting soaked in a rainstorm makes you cold, its not just because the precipitation moistens your clothes and skin, the temperature of the rainwater itself is also to blame. On average, raindrops have temperatures somewhere between 32 F (0 C) and 80 F (27 C). Whether a raindrop is closer to the cold or warm end of that range  depends on a number of things including what temperature it starts at high up in the clouds and what the air temperatures are in the upper atmosphere where those clouds are floating. As you can imagine, both of these things vary from day to day, season to season, and location to location, which means there is no usual  temperature for raindrops.   Temperatures in the atmosphere interact with raindrops, starting from their birth high up in a cloud to their final target- you and the ground- drastically affecting the temperature of these droplets of water. Cold Beginnings and Cold Descents Surprisingly, most of the worlds rainfall begins as snow high up in the clouds overhead- even on a hot summer day! Thats because temperatures in the upper portions of clouds are well below freezing, sometimes as low as -58 F. The snowflakes and ice crystals found in clouds at these cold temperatures and heights warm and melt into liquid water as they pass below the freezing level, then exit the parent cloud and enter the warmer air below it. As the melted raindrops continue to descend, they can become cooler through evaporation  in a process that  meteorologists call evaporative cooling,  wherein rain falls into drier air, causing that airs dewpoint to increase and its temperature to lower. Evaporative cooling is also one reason why rainfall is associated with cooler air, which explains why meteorologists sometimes claim it is raining or snowing high up in the upper atmosphere and will soon do so out your window- the longer this happens, the more the air near the ground will moisten and cool, allowing the precipitation a path to fall to the surface. Air Temperatures Above Ground Affect Final Raindrop Temp In general, as precipitation nears the ground, the atmospheres temperature profile- the range of air temperatures that the precipitation passes through- from around the 700 millibar level down to the surface determines the type of precipitation (rain, snow, sleet, or freezing rain) that will reach the ground. If this temperature is above freezing, the precipitation will, of course, be rain, but how warm above freezing they are will determine how cool the raindrops will be once they hit the ground. On the other hand, if the temperature is below freezing, the precipitation will fall as snow, sleet, or freezing rain depending on how much lower than freezing the range of air temperatures is. If youve ever experienced a rain shower that was warm to the touch, its because the rains temperature is above the current surface air temperature. This occurs when temperatures  from 700 millibars (3,000 meters) down are quite warm but a shallow layer of cooler air blankets the surface.