dont warm it up you will destroy the probiotics effect but example if you do water kefir just leave it out on your counter and drink it after a couple of hours but some of the kefir you can leave it out and some you have to store it in the fridge

Actually what I have done is: pour half a mug of kefir drink, fill it up with lukewarm water. The result: a mug full of not very cold half strength kefir. I expect that does not affect the probiotics?
PS nice picture you gave me .....