Corner protectors can be used on cloudy and rainy days. In the construction industry, corner protectors usually refer to corner protection panels or strips, which can be installed in corners to protect walls and furniture. Corner protectors can be used on both sunny and rainy days, but in humid weather, they may become damp, which can affect their functionality.

If it refers to corner protection material, it can be used in rainy days. For example, paper corner protectors are widely used in transportation and storage to protect products from damage during transportation. These corner protectors can be used on both sunny and rainy days, but they may become damp in humid weather.

Overall, corner protectors can be used normally on rainy and cloudy days, but corresponding protective measures need to be taken in damp weather to avoid the impact of moisture on the corner protectors.