Sandstorms are naturally occurring events exclusive to Don't Starve Together, introduced in A New Reign. They happen during Summer inside the Desert Biome with the Oasis and Antlion. Sandstorms last the whole Summer, except during rain and while the ground is wet.
Wilson in a Sandstorm without Desert Goggles.
When entering a Desert during a Sandstorm, the player's Field of Vision will instantly be limited, disabling the ability to see anything but a small area around the character. Additionally, movement speed will be reduced by 60%. In order to avoid becoming blind to the Sandstorm, one must be equipped with Desert Goggles. Furthermore, while being inside of the Sandstorm, the player will not cause any Summer smoldering around themselves. This effect persists to areas outside of the Desert, as long as the player is inside of the Sandstorm.
During rain, sandstorms will temporarily cease until after the ground is dry from the rain. Smoldering does not occur during rain or while the ground is wet, making the Oasis Desert an excellent protection against Summer Smoldering.