How Can the Weather Affect the Rate of Metal Rusting?

Rusting metal around the home is unsightly, pollutes the soil and groundwater with excess rust and can permanently damage whatever is rusting. Whether the metal is in the garden, on the home or on your lawn furniture, you want to prevent its rusting if at all possible. Understanding what processes instigate and speed the development of rust help you know whether you need to do more to protect your property against rust.

...
Several factors from the weather affect the rate at which rust forms.

Moisture

In a hot and dry climate, metal is much less prone to rusting than in a humid or wet climate. Rust is the byproduct of a process called "corrosion." Metal corrodes when it goes through a chemical reaction involving the oxygen in water. If the metal is kept dry at all times, it is much less likely to start rusting than if it is constantly being exposed to rain or to high humidity that condenses on the metal.

Temperature

Heat also plays a part in how fast metal rusts. Generally speaking, higher temperatures are associated with higher rates of corrosion. Therefore, the temperature caused by the weather may affect how fast metal rusts. You can generally expect less rust in the winter and more in the summer; however, this can change based on other factors. For instance, a lower temperature but increased humidity could still lead to increased rust.

Winter Weather

Winter weather affects the rate of metal rusting from a cause beyond the temperature and moisture factors. When a region receives a great deal of snow or ice on the roads, the result is that the local department of roads or highways will put salt or other de-icing substances down on the roads. Salt and other substances put down to deal with icy roads greatly increase the rate at which rust forms on buildings, vehicles and other structures.

Acid Rain

Although all rain will speed up the rate of corrosion, acid rain will accelerate it much more. Acid rain can be caused by pollution and unregulated industry, and natural occurrences such as volcanic eruptions also contribute to the problem. Any metal on buildings, cars or on a property will rust faster if exposed to prolonged bouts of acid rain. The speed at which acid rain accelerates rust depends partly on how low the pH of the water has dropped compared to a normal level of 5.6.