This is not true. There are two causes for the changes of seasons. The inclination of the Earth s axis, or the tilt of the Earth is always the same at 23.5 . This angle does not change as it travels in its orbit around the sun. Summer occurs when the rays of the sun are the most vertical on a particular place on Earth.
Winter occurs when the sun s rays are the most slanted on a particular place on Earth.
Since the rays of the sun are most direct in the tropics all year, the seasonal temperature there change very little except at higher altitudes.