How to forecast the weather in Shijing, Dongkou County?

There is a square ancient stone well with a length of 1.5m and a depth of 2m in Hechi Village, Zhu Shi Town, Dongkou County, Hunan Province. For hundreds of years, people have been drinking well water, and there is nothing unusual. In recent years, this well is a bit abnormal. Every day before the rainstorm, the well water will turn brown bitter, but it will return to its original state after 3 to 5 hours. Every time it is accurate, it is called "magic weather forecast well" by locals.