Parenting toddlers often reminds me of the beginning of Rudyard Kipling's poem "If",
If you can keep your head when all about you are losing theirs and blaming it on you . . . .
If Mr. Kipling was alive, my questions to him would be:
How to you keep your head when the toddlers in your life are losing theirs? and
How to you keep the toddlers in your life from losing their heads in the first place?
There are plenty of books on preventing and managing toddler tantrums. My new favorite, Calm-Down Time, is written for toddlers to help them learn how to regulate themselves.
We have seen this book help multiple children at the school and I use it at home with my own children. It is not an instant solution but it definitely does not hurt! And, even if it does not stop the toddler's tantrum, reading the book gives the adult-in-charge a chance to pause so at least one person can keep their head!