The notion that it becomes warmer at dusk is a common misconception. In reality, the temperature starts dropping as the sun goes down. The perception of increased warmth likely arises from the following reasons:

1. Wind Shift: As the sun sets, wind patterns often change, becoming calmer. This can reduce wind chill and make the air feel more pleasant, giving the impression of increased temperature.

2. Human Factors: Our perception of temperature can be subjective, and various physical factors can influence how we feel. For instance, as the sun goes down, there is a decrease in light intensity, which can make our bodies work harder to maintain internal temperature, leading to a perception of warmth.

3. Body Adaptation: Our bodies naturally experience fluctuations in temperature throughout the day, with a peak in the late afternoon and a drop in the evening. This diurnal rhythm can sometimes result in a subjective sensation of increased warmth just before dusk, even if the actual temperature is decreasing.

4. Microclimate: Local microclimates, such as sheltered or enclosed spaces, can retain heat more efficiently, making them feel warmer during transition periods like dusk.

5. Humidity: If the humidity level is high, the body's ability to cool itself through sweat evaporation decreases. This can lead to a sensation of increased warmth, even if the temperature doesn't rise.

6. Contrast Effect: The stark contrast between the warm daytime temperatures and the cooler evening air can create a perceived sense of warmth during the transition period around dusk.

It is important to note that weather and temperature changes can vary depending on location, time of year, and individual perception, so the experience may differ from person to person and place to place.