Frost can greatly impact a grower's yield. When temperatures dip below 32 degrees F, and buds have already started to swell, they run the risk of freezing over. If the buds freeze over, they won't bloom, and without bloom, the tree cannot produce fruit.
Water freezes at 32 degrees F, but the buds don't start getting damaged until about 29 degrees F. During these temperatures, if there is no inversion event, growers will turn on irrigation to freeze the bud which acts as insulation and protects it from damage. If there is an inversion event, growers will turn on frost fans.
Looking at the absolute temperatures of each SCD, you can see that frost generally doesn't occur until 4:30 or 5:00 AM, and frost risk can develop in a matter of minutes. Because of this, growers will often not sleep if they know the frost risk is high.
During this time, growers will also be heavily using frost alerts, frost control page, and frost inversion function.