At four in the morning UTC, April First, the Moon reaches its low point in the sky, from our southern point of view. It will start descending for those of you in the Northern Hemisphere. In either case, this may be another aspect that toys with our weather effects.
To describe the duration, please see the sine curve, wikipedia.org/wiki/Sine_curve, as with tides and seasons, the effects of Low or High Tide, or Winter or Summer are the extremes that last most of the cycle. The apparent changes are quickest at the swing from one to another, for example, Spring and Autumn have short durations, as the daytime minutes are rushing to change at almost three minutes per day at these latitudes now, near the equinox.
These cycles are not identical every year, but this year, the Moon will be in Taurus, close to the low Ascendent. Biodynamic farmers use this for planning activities, and have had great successes. The Ascending or Descending effect on the weather will be a challenge to track.