In New Leaf
Some larger snowflakes occasionally appear during December, January, and February when it is snowing. Though they may also appear even if the weather is clear and if a Snowman is present in the town. They can be caught with a net and traded to Snowmam for Ice furniture. They can also be sold to Re-Tail for 500 Bells. Snowflakes cannot be stored in storage units, placed as furniture or dropped outside. When the player is outside they have the option of either showing it off, as if it were a catch, or throwing them away permanently.
Snowflakes make a quiet twinkling sound when in vicinity of the player.
In New Horizons
Snowflakes return and can be seen floating through the air to be caught with the players Net from December through February (Northern Hemisphere) and June through August (Southern Hemisphere). Like in New Leaf, snowflakes make a light twinkling sound when the player is near them. Similarly to Cherry-blossom petals during the Cherry Blossom Festival, if a player runs through or by a floating snowflake, it will disappear. Attempting to catch a snowflake and missing can also trigger its disappearance if the players net was swung too close.
Snowflakes are used in crafting furniture from the Frozen Set (New Horizons) as well as various other festive diy recipes. They vary in that there are normal snowflakes and large snowflakes. Large Snowflakes can only be obtained by creating perfect Snowboys and will be gifted to the player by them once per day along with DIYs from the frozen series. If a player has multiple perfect Snowboys on their island, they can receive one large snowflake from each Snowboy. Imperfect Snowboys will not reward the player with any large snowflakes.
Unlike in New Leaf, Snowflakes in New Horizons cannot be gifted to villagers. They can, however, be stored or placed like furniture.