One factor that may get forgotten in the rush to do an aerial job is the effect of the weather on your drone, more specifically the air temperature on a multicopter’s performance. Most know of the impact temperature has on LIPO batteries, but the impact extends beyond just this.
Most pilots are aware of the effect altitude has on the performance of the power system and props, the higher you are the less thrust gets produced due to the thinner air density. The same effect also happens with increased ambient temperature. As the air temp increases the air density drops and in turn so does thrust. Humidity also impacts this effect as well. Generally, thrust decreases with an increase in ambient temperature.
This is commonly referred to as Density altitude. As defined in Wikipedia:
Density altitude is the altitude relative to the standard atmosphere conditions (ISA) at which the air density would be equal to the indicated air density at the place of observation. In other words, density altitude is air density given as a height above mean sea level. “Density altitude” can also be considered to be the pressure altitude adjusted for non-standard temperature.
Both an increase in temperature, decrease in atmospheric pressure, and, to a much lesser degree, increase in humidity will cause an increase in density altitude. In hot and humid conditions, the density altitude at a particular location may be significantly higher than the true altitude.
When operating in hotter conditions be aware of the effect and make sure your system has adequate thrust and performance to overcome the conditions.