You wouldn't think stones would only cause issues when it gets colder. However, ulcers might be something to contemplate if the episodes only occur at certain times, which could be stressful for a particular equine. I had a sensitive mare that I thought was colicing, but turns out she easily stressed and would get mild to moderate ulcers, so for things I knew would stress her, I gave her an ulcer prevention product. The go to product I had at the time is not longer available, but there are plenty of products on the market to try and see if any of them keep her comfortable during times you think might be a problem. It might not be ulcers, but trying an ulcer prevention product starting at least a few days before you think she might normally have a colicy reaction.