We have to be aware the scale of the drops of water vs the size of bees themselves. Yes this can affect their flight however it’s normal to see them go about foraging during a light shower. Although there’s no way in tempting them to leave the safety of their cosy hive during a heavy rain or thunderstorm. Studies have shown that bees behave differently before astorm. They have been found to forage the evening before a storm, so it seems they can sense the changes in air pressure long before the storm hits. They also tend to get less charitable with their honey stores, so you’ll notice that they’ll be more aggressive at that time. This is also a reason why many beekeepers tend not to inspect their hives during this period due to their temperament change.