The bees will be attracted to the moisture in the mist of the spray until it drys as moisture that they will bring into the hive. If you have running water close enough to set a sprinkler on the hives this is the best and safest. cover the hives with a white sheet and with the sprinkler raining down over head the bees think it is raining and stay inside it also dilutes the chemical in any spray mist that makes it to the hives. One the spray mist is dry remove the sheet and let the bees fly.
If water is not close by I would screen them in and use a white plastic sheet draped loosely to protect against spray mist. 61 deg is on the edge of bee forage weather that is listed at 62 deg so the bees will want to fly before the chemical mist is dry. If the winds or breeze is favorable away from the hive then you will not have to worry about the chemical mist drifting into the hives, if not then it can be an issue. If possible providing the bees with water in an in-hive, Hive top, or feed jar, will give them the water they need to air condition the hive if they get to hot.