The answer to whether it can snow and rain at the same time is yes. Meteorologists call this common weather event mixed precipitation, which signals a transitional phase in the atmosphere. It often occurs as a winter storm begins to warm or an unseasonably warm spell moves out of a region. The presence of both liquid water and ice crystals simultaneously indicates a very specific, narrow set of conditions high above the ground.
Defining Mixed Precipitation
Mixed precipitation, specifically the rain/snow mix, is characterized by a slushy, wet combination of raindrops and partially melted snowflakes. It looks and feels heavier than pure snow because of the higher water content. This mix occurs when snowflakes that formed high in the atmosphere only partially dissolve on their way to the surface.
This precipitation type happens when the air temperature near the ground hovers just above the freezing point, typically between 0°C and 2°C (32°F and 35.6°F). Since some snowflakes are larger or denser than others, they resist the melting process long enough to retain their crystalline structure. The result is a precipitation event where some ice crystals survive the descent alongside fully formed raindrops.
The Necessary Atmospheric Conditions
The ability for both rain and snow to fall at once requires a highly specific arrangement of air temperatures in the vertical column of the atmosphere. This setup involves three distinct layers. All precipitation originates as snow in the frigid upper cloud layer where temperatures are well below freezing, often colder than -12°C.
As snowflakes fall, they encounter an intermediate layer of warmer air, known as a thermal inversion, where temperatures climb above 0°C. This warm air layer, which can be several hundred meters thick, is where melting begins. If the warm layer is too shallow, smaller snowflakes melt entirely, while larger ones only partially melt.
The final layer is the air closest to the surface, which must be near freezing but still slightly above 0°C (32°F). The partially melted, slushy snowflakes and the fully melted raindrops pass through this layer together. They hit the ground as a mixed precipitation event. This unique temperature profile, often described as a warm air “sandwich,” allows both phases of water to coexist upon impact.
Distinguishing Other Winter Precipitation Types
Slight changes to the vertical temperature profile can result in entirely different winter precipitation types, such as sleet or freezing rain. Sleet, also called ice pellets, begins identically to mixed precipitation, forming as snow in the high, cold cloud layer. For sleet to form, the snowflake must pass through a deep enough warm layer to melt completely into a liquid raindrop.
The key difference for sleet is the presence of a second, deep layer of sub-freezing air just above the ground. This cold layer must be deep enough to allow the melted raindrop to completely refreeze into a tiny, solid ice pellet before reaching the surface. These hard pellets bounce upon impact, distinguishing them from the wet slush of a rain/snow mix.
Freezing rain, in contrast, results from a very deep warm layer followed by a very shallow cold layer near the surface. The snowflake melts completely into a raindrop in the extensive warm air. The sub-freezing layer near the ground is not deep enough to allow the drop to freeze in the air. Instead, the liquid becomes “supercooled,” remaining a liquid even though its temperature is below 0°C. The supercooled liquid then freezes instantly upon contact with any surface that is at or below freezing, creating a dangerous glaze of clear ice.