Water is lost by evaporation and by transpiration from plants’ leaves. Wind makes transpiration act faster as the damp air near the leaves is constantly moved away, allowing more water to be expelled through the pores on the surfaces.
Sun, of course, will also dry both soil and plants. You can reduce the sun’s impact on water levels by covering the soil with groundcover plants or with a mulch to help slow evaporation, bare soil is going to lose water fast. It is worth spending money on bark mulch or compost to cover the soil after rain or watering in order to save expensive plants. Further rain will permeate course mulches and be held, protected from evaporation, in the soil below.
Delivering water in a slow and controlled way is best, if like me you grow fruit and veg this will improve your crop a much as anything. A DIY fix is to use 2 terracotta pots to make a permeable reservoir which you plant next to thirsty crops. Use sealant/glue to stick the pots together, and to fill in one of the drainage holes. This is buried so only the top with the open hole showing. when watering fill the pots and water will seep out slowly, whilst the plant will develop roots that wrap around it.
For my greenhouse I have a self watering setup to bring rain inside. This doesn’t replace the need to water manually when it is dry, but means it can largely look after itself in wet weather.
You will need flexible pipe (vacuum cleaner hose), a reservoir for water (petrol can), milliput and some drip hose. The hose is fixed to the gutter and the petrol can with the two part putty, and drip hoses are put into holes in the can in the same way. In order to bring the ‘in’ pipe inside, a glass sheet is replaced with plastic so a hole can be cut. The ends of the lines are blocked to make water seep from all the length. If there is no rain you can fill the reservoir with a watering can to add water over a period.