I do my load-development during the winter months as well, that's just when there's time I guess. Because I use my rifles mostly to hunt, (and since hunting season is generally cold anyway) winter load developing works perfect for me. I just try to use days that are most-similar to my hunting-season temps for finalizing my loads...
Once I have one done, I'll then verify what that load is doing in THAT temp.. and make a note of it. Then check it when temperatures dip to the most extreme-temperature you figure you'll be faced with (or are comfortable enough to shoot in) And then, once spring rolls along, go out once more and shoot that very same load again-- again noting changes or swings in velocity, while looking for pressure signs* if any show up
Generally, with any extreme-line of Hogdon powder which is more-so stable than most others, so long as a guy isn't settling on a MAX charge on the line of pressuring when doing your load development in the winter, your pressure shouldn't spike into the danger zone after the grass turns green and coveralls turn to t-shirts. Only way to really be sure is to shoot and test it as the mercury climbs and note what is happening. That's really the only way to know if different powder charges are absolutely necessary or not.
**if there is a load or a reason to specifically be shooting in hot-weather, my suggestion would be to re-evaluate the load in the rifle you want to shoot (in that specific temperature) and focus on your powder selection and load to do just that. If it's an all-arounder type of load/rifle, I'd find a balance and settle on a load the way I first described myself doing. It does work good for me.