During some mornings in Yosemite Valley, when the weather is below freezing, you can see a rare phenomenon called "frazil ice" at the base of the waterfalls. These are small ice crystals of frozen mist that float down the creek and form a moving stream of slush that looks like frozen lava! It usually occurs in the morning, before 9 am.
Frazil ice is often accompanied by another phenomenon called the snow cone which occurs when falling water from the falls freezes before it hits the ground and piles into a large cone of ice.
You can often witness frazil ice in spring, especially in April, but sometimes in March and May as well.
Practical info
When is the best time to witness the frazil ice phenomenon in Yosemite Valley?
Frazil ice can be witnessed during the early morning hours when the temperature in Yosemite Valley falls below freezing. Springtime, mainly April, is the best time to see this phenomenon, although it may occasionally occur in March or May. Once the sun has risen high enough to warm the valley, the opportunity to view the frozen mist vanishes. Show more
What is frazil ice and how does it form?
Frazil ice forms when temperatures in Yosemite Valley are below freezing. It happens when water from the Yosemite Falls freezes and forms small crystals of ice. This mist of small particles of ice flows downstream, creating a stream of slush. The process occurs because the water molecules in Yosemite Creek are unstable and bond together once the temperature reaches below the critical supercooling point. Show more
Can we see the frazil ice phenomenon in any other place in Yosemite apart from Yosemite Falls?
The frazil ice phenomenon can only be witnessed where waterfalls occur in Yosemite Valley, and it's most dense at the base of the cliffs. Yosemite Falls, one of Yosemite's prominent waterfalls, is the best place to witness the event since the waterfall may stop flowing during winter, allowing for a better view of the phenomenon. No other location in Yosemite lays claim to this rare natural occurrence. Show more
Is it possible to predict the occurrence of frazil ice before visiting Yosemite Valley?
Frazil ice is difficult to predict, but it often happens during early spring before 9 am when the temperature is below freezing. Due to rapidly changing climate conditions, however, it is not feasible to pinpoint the exact time the phenomenon will occur. It is advisable to check Yosemite's weather reports and forecasts before visiting the valley for this rare event. Show more
How long does the frazil ice phenomenon last and what is the best time of the day to catch a glimpse of it?
Frazil ice lasts for a few minutes to an hour on average, depending on the weather conditions in Yosemite Valley. The best time to see it is in the early morning hours before 9 am, when the temperature is below freezing. Once the sun rises and warms the air, the chances of seeing the event decrease. Therefore, early morning is the best time to catch a glimpse of it, and visitors are encouraged to arrive early to select the best vantage points. Show more
