Increasing rates for winter/repeat clients?

So I’ve been on Rover since May, and have since gained 3 repeat clients and have five 5 star reviews (not much I know lol, but I’ve been intentionally pretty picky.)

I am considering raising my walking rates, as this are where I book most of my clients and I live in a VERY seasonal location with long cold winters that start around now. However, I am unsure how much to raise my prices by and whether or not to lock rates for my current clients or raise them across the board. I also have a client who I absolutely adore and do not want to lose, but I can’t find a way to lock their rates because they have a repeat booking twice a week.

Is it appropriate to raise my rates, or should I wait for more reviews/just deal with the weather? Has anyone had any luck locking rates for repeated/regular bookings? If not, how should I notify my client, and what kind of a price raise might be appropriate without losing them? For context, I currently charge around the avg rate in my area— I’m a dollar higher than about 2/3 of the other walkers, but 4-6 dollars lower than the other third. Thanks all!!!!!