Sometimes in very hot weather, I find my hanging baskets need more than just one watering. I just try to avoid the very middle of the day, and try to water the compost not the plants.

You may have already done these things, but hanging basket compost generally has water retentive properties and there's also moisture control gel available. As melchisedec advised, avoid watering in the heat of the day and really soak the compost avoiding watering the plants.

Personally I'm hoping for some rain - running out of the rain water we collected!

My water butt that was overflowing is now empty.

I water my baskets not plants the soil early morning and last thing at night.

Or have a water bottle drip .

When the weather is very hot like now, water early in the morning, and again in the evening, so twice a day. I use an old 1.5 litre Evian water bottle, because its easy to push it under the foliage and pour slowly and steadily into the compost. Also useful because you know how much water its had - but if the water starts to run off within seconds, the compost has become very dry and isn't absorbing the water. That means you have to trickle the water in very slowly. Then go back and do it again about half an hour later, or the compost won't be damp at all.

In hot weather, I do all the watering I'm allowed to do very, very early in the morning - that way the plants have an opportunity to take it up before evaporation occurs. With baskets, the same. I couldn't possibly improve on Bamboo's advice. Twice a day and never let the compost dry out.

I have an angled plastic funnel thing that fits onto a lemonade bottle. It has a long arm/handle so I can reach the basket, and I stick the spout into the compost. As Bamboo says, then you can see how much water is actually being absorbed. I think I got it from Betterware (or Kleeneeze - always get them mixed up!). But there are several watering aids that are good.