You can request pre-warming for additional ELB capacity, when you know far enough in advance that you will have a spike. AWS customer service responds by asking 10 clarifying questions via email. The thing is, we can't look under the hood to see currently provisioned and utilized ELB capacity, so we just have to trust that AWS engineers will properly allocate resources according to the answers to those questions. IMO, it's a rather cumbersome process that would be better implemented as a form.