Which factor affects density altitude the most?

The factor that affects density altitude the most is temperature. Density altitude is a calculation that represents how high an aircraft feels it is performing relative to its actual altitude. It is impacted primarily by temperature because as temperature increases, air molecules become more spread out, which decreases air density. This is why warmer air is less dense than cooler air.

Higher temperatures lead to a higher density altitude because the aircraft is operating in a less dense medium, which can adversely affect lift, engine performance, and the overall performance of the aircraft. Conversely, when the air temperature is lower, density altitude decreases, resulting in better aircraft performance due to denser air.

Other factors, such as wind speed, humidity, and time of day, can influence flying conditions but do not have as considerable an effect on density altitude compared to temperature. Wind speed does not change the density but can affect how air is distributed around terrain. Similarly, humidity adds some weight to the air mass but its effect on density is less significant. Time of day can influence temperature but it is the temperature itself that has the direct and most substantial impact on density altitude.