What do you mean the appearance of rainbow is related to the weather change at that time?
Rainbow is a natural phenomenon, which is caused by the reflection and refraction of light when sunlight hits water droplets in the air.
rainbows are caused by the dispersion and reflection of light when sunlight hits small round water droplets in the air. When sunlight enters the water droplets, it will be incident at different angles at the same time, and it will also be reflected at different angles in the water droplets. Among them, the reflection of 4-42 degrees is the strongest, forming a rainbow that people see.
In fact, as long as there are water droplets in the air and the sun is shining at a low angle behind the observer, an observable rainbow phenomenon may occur. Rainbow usually appears in the afternoon, just after rain, when it clears up. At this time, the air is less dusty and full of water droplets, and one side of the sky is dark because there are still rain clouds. However, the observer can see the sunshine without the cover of clouds on his head or behind him, so that the rainbow can be seen more easily. The appearance of rainbow is related to the weather change at that time. Generally, people can infer that it will be sunny or rainy at that time from the position where rainbow appears in the sky. When there is a rainbow in the east, it is not easy to rain locally, but when there is a rainbow in the west, it is very likely to rain locally.
The visibility of the rainbow depends on the size of water droplets in the air. The larger the water droplets are, the brighter the rainbow will be, while the smaller the water droplets are, the less obvious the rainbow will be. Generally, the temperature in winter is low, so it is not easy to have small water droplets in the air, and there is less chance of rain, so there is generally no rainbow in winter.