It spins on its side so that the sunny side does not rotate into darkness for a 'night' during it summer. All summer is the same as all day for about 42 years. As this long orbit continues, it does become winter and night for the other half of the Uranus year. Because Uranus is so far from the sun, it is always hot cocoa season whether you sip it in the dark or in the thin sunlight. For all planets in our galaxy, the seasons depend on the way the planet tilts toward the sun, how the planet spins on its axis, and the length and path of its orbit around the sun.
Sunlight makes warmth.
Darkness means colder temperatures. As you think about seasons here and there, it is easy to conclude that Earth's seasons are just right. The time when the sun crosses the equator, making night and day of equal length in all parts of the Earth. Marks the beginning of spring and is often called the vernal equinox. It occurs on March 20 or 21.