I guess compared to winter (0°C), the juice is now +35°C warmer for vaporizing, the coil or atomizer might draw better. Maybe it doesn’t need such long heating…
“Temperature dependence: Viscosity is strongly temperature-dependent. In the case of liquids, viscosity decreases with increasing temperature (they thin out), while for gases it’s the opposite: viscosity increases with increasing temperature.”
Poor vapor! 
