National Hippo Day is Feb. 15. Help us Bring Hippos Back to Cincinnati! February 14, 2014 February 15 hippo national hippo day National Hippo Day is February 15, and we are asking for donations to help us complete the final phase of our Africa exhibit — the hippo pool! Help Bring Hippos Back to Cincinnati! Text HIPPO to 80888 to donate $10 (charged to your cell phone bill) or click here to make a credit card donation in any amount.