Isabella and the Magic Umbrella by Kate Mahoney-Veitch

Isabella is having a tea party outside and it starts to rain.  She runs in for an umbrella.

The author shared this book with me for a review (thank you).  It has been published and you can grab a copy now.

When she opens the umbrella, the rain stops.  When she closes it, it starts raining again.  After testing it several times, she leaves it open and they all have their tea party.  I need one of those umbrellas!

They decide it's magic and a beautiful rainbow blossoms in the sky.

Sarah-Leigh Wills has done the illustrations.  This is another in the Isabella series and they are all charming.