Suddenly it was dark. Does it mean heavy rain or light rain?

The weather will suddenly get dark before the heavy rain comes. When the rain is light, the weather is normal and will not get dark.

Signs of rainstorm: 1. It is sultry in the morning, and it is difficult to breathe. It is generally a sign that the low-pressure weather system is approaching, and there is often heavy rainfall in the afternoon. 2。 In the morning, I saw a pagoda-shaped ink cloud uplift in the distance, and there was usually a strong thunderstorm in the afternoon. 3。 For several days in a row, the weather was clear and cloudless, especially hot. Suddenly, I saw a small cloud rising on the windward slope of the mountain, and there was usually a strong thunderstorm at midnight or early morning. 4。 On a hot night, hearing the dull thunder not far away is usually a sign that a storm is coming.