Whenever the weather, during the period of free time, is so severe, inclement, or rainy that it is impossible or impracticable to secure means of loading or unloading freight, or when, from the nature of the goods, loading or unloading would cause injury or damage, then additional time shall be added to the free period, and no demurrage charges shall be allowed for the additional free time. This applies to the state of the weather during business hours.