Wilting plants and shrubs do not always need water when sunny weather returns after a rainy period. In fact, the soil might be saturated making extra moisture one thing the shrubs and plants do not need.
Periods of rainy weather saturate the soil with water, forcing air out of the soil so roots cannot breathe. This sometimes causes root death and plant growth slows down due to lack of oxygen and buildup of other gasses such as carbon dioxide or ethylene.
As sunny weather returns, plants become stressed and begin to rapidly lose moisture through the leaves. However, they cannot replace the moisture fast enough because water-saturated soil has stressed the roots. Once the soils become less saturated, the roots usually will re-grow and shoot growth will resume.
Waiting a while before watering usually will alleviate the saturated soil situation.
Like many guidelines, these tips have an exception that pertains to potted plants.