It is said that we should water less in Autumn and Winter. However in Winter, our hands and face become very dry. Doesn't this indicate a low relative humidity and that water will dry out faster?
Humidity in winter will vary a lot according to climate. In the UK, yes your face might dry out and relative humidity may be a part of it, but the wind plays a part.
Plant soil dries out due to evaporation (which you are thinking of) and the plant's natural evapo-transpiration processes (ie. what it "drinks"). Most plants slow down and even become dormant (eg. deciduous trees) during winter. Hence they require less water because growth is minimal or stopped.
This process starts in Autumn as the weather cools and light levels are reduced. In contrast, in Spring, the plant is starting to "wake up" and needs water to function.
This may seem non-responsive to the question - and it is, in that I'm suggesting that it may be the wrong question.
Instead of trying to estimate from weather and climate, let the soil tell you when to water. That way all of the variables relative to that specific plant, pot?, soil, and siting will be taken into account.
Water only when it's dry. But don't wait beyond then. This will encourage deep roots without over-stressing the plant.
How dry is dry? The soil should be dry to the touch. Depending on the soil, it will usually be a lighter color than when it's moist. If you poke into the soil, say 5-10 mm, you won't find moist or darker soil just underneath the surface.
I don't mean to discourage having a schedule for usually watering. But always check the soil - at least feel the surface a bit. Every once in a while you'll be really surprised.