Today is autumn equinox. The night and the day are theoretically equally long everywhere on Earth. Why theoretically? In practice, the apparent position of the Sun is higher in the sky that its real position because sunlight has to pass through the atmosphere. As the density of the atmosphere varies at different altitudes sunlight is bent slightly. This is why the time between sunrise and sunset is not exactly 12 hours but somewhat longer. It's actually 12 hours and 14 minutes today here at the 61st northern latitude. The sun rose at 7:02 am and it will set at 7:16 pm today. In Manaus, Brazil, at almost exactly on the equator, it the length of day is 12 hours 7 minutes today.
Why the difference? That's because when the Sun is closer to the zenith (the center of the sky), the atmosphere will bend it's path (downwards) to a lesser degree than when the Sun is closer to the horizon. This is why we get the seven-minute difference in the length of day at the equinoxes. Even without the atmosphere, the length of day would be some minutes longer than exactly 12 hours because the Sun is a disc and not a dot. Sunset is defined as the moment when the upper edge of the solar disc has disappeared behind the horizon and sunrise is defined as the moment when the upper edge of the solar disc appears from behind the horizon.
As you can see from the images below, it is starting to look like proper autumn. However, thermal summer is not about to end for at least a week. The daily maximum is forecast to be 20 C on Thursday and Sunday. It's basically going to be a summer day. The rest of the week will see daily maximums above 15 C and the nightly minimums will not go much below 10 C. The thermal summer just won't let up.