Physical natural conditions that trigger drought are:
Very less precipitation
One of the major causes of drought is very less precipitation or no precipitation at all.
Precipitation rates vary every year and also vary from region to region.
When the precipitation rate is less than the average and it sustains for a longer period of time, it results in droughts.
High-temperature changes and wind pattern changes are factors that lower the rainfall rates.
El Nino
El Nino effect is the change in ocean temperature due to the combined effect of atmospheric changes and ocean currents.
This effect gives rise to very hot, dry weather resulting in droughts.
Dry season
The dry season is a season in regions with tropical climates.
It is the season without any rainfall which comes every year.
Low humidity is the main characteristic of this season.
Thus, the evaporation rates are extremely high during this season
This dries up almost all the water bodies, thus resulting in droughts.
This season is also prone to higher temperatures and hence it worsens the droughts.