Can Wet Hay Catch On Fire?

Hay is a common material used for various purposes, from animal feed to bedding. But have you ever wondered if wet hay can catch on fire? In this blog post, we will explore the intriguing question surrounding wet hay and its potential fire hazards.

Stay tuned as we delve into the science, factors, and safety precautions associated with this curious phenomenon.

Whether you’re a farmer, animal enthusiast, or simply curious about the world around you, this blog post is sure to provide valuable insights. So, let’s get started and uncover the truth about wet hay and its flammability.

Can Wet Hay Catch On Fire

Can Wet Hay Catch On Fire

Yes, wet hay can catch on fire under certain conditions. While wet hay is less likely to ignite than dry hay, it can still combust if the right circumstances are present.

When hay gets wet, it can undergo a process called “spontaneous combustion” if it is baled or stored improperly.

Spontaneous combustion occurs when moisture in the hay triggers microbial activity, which generates heat. If the heat is not dissipated and the temperature continues to rise, it can eventually reach the point where it ignites the hay.

This is more likely to happen in large hay bales or stacks where heat can build up and air circulation is limited.

Why Does Wet Hay Catch On Fire

Wet hay can catch on fire due to a process known as spontaneous combustion. This phenomenon occurs when certain conditions are met:

Moisture Content: When hay is wet, it typically has a higher moisture content. Microbes, such as bacteria and fungi, thrive in a moist environment.

Microbial Activity: Microbes naturally inhabit hay, and when the hay is wet, they become more active. As they consume organic matter within the hay, they release heat as a byproduct of their metabolic processes.

Insulation: Hay bales can act as insulators, trapping the heat generated by microbial activity within the bale. This can cause the temperature inside the bale to increase.

Limited Ventilation: Poor ventilation around the hay bales can prevent heat from dissipating into the surrounding air. Without adequate ventilation, the heat becomes concentrated within the bale.

As the temperature inside the wet hay bale rises due to microbial activity and poor ventilation, it can eventually reach a point where it is high enough to ignite the dry, flammable hay material. Once ignition occurs, a fire can spread throughout the hay bale.

How To Reduce The Risk Of Wet Hay Fires

Reducing the risk of wet hay fires involves proper handling, storage, and monitoring practices. Here are steps you can take to minimize the risk:

Proper Drying: Ensure that hay is properly dried in the field before baling. Hay should be dried to an appropriate moisture level, which typically ranges from 15% to 20% depending on the type of hay. Use a moisture meter to check the moisture content before baling.

Bale at the Right Moisture Level: Avoid baling hay when it’s too wet. If hay is too moist when baled, it can increase the risk of spontaneous combustion. Bale hay at the recommended moisture level for your specific type of hay.

Use Good Baling Practices: Follow proper baling techniques and use well-maintained equipment. Make tightly packed and uniform bales to reduce the potential for air pockets within the bales, which can contribute to heat buildup.

Store Hay Properly: Store bales in a well-ventilated area that allows air to circulate around and through the bales. Elevate bales off the ground on pallets or other supports to prevent moisture from being absorbed from the ground.

Monitor Temperature: Regularly monitor the internal temperature of stored hay bales, especially during the first few weeks after baling when the risk of spontaneous combustion is highest. Use temperature probes or long-stemmed thermometers to check the temperature within the bales.

Rotate and Inspect Bales: Periodically move and inspect hay bales. This helps break up any hot spots that may develop within the stack of bales. If you detect elevated temperatures or signs of heating, take corrective action immediately.

Separate Problem Bales: If you find a bale that is excessively hot or showing signs of heating, remove it from the storage area and allow it to cool in a safe location away from other bales.

Properly Dispose of Problem Bales: If a bale has ignited or is smoldering, do not attempt to extinguish it with water, as this can be dangerous due to steam and hot gases. Instead, contact your local fire department for assistance.

Educate and Train: Ensure that all individuals involved in hay production and storage are educated about the risks of wet hay fires and the proper procedures for prevention and response.


Is wet hay more flammable?

Wet hay is generally less flammable than dry hay, but it can still catch fire under specific conditions, such as when it undergoes spontaneous combustion due to microbial activity and poor storage practices.

Can wet hay bales catch fire?

Yes, wet hay bales can catch fire due to spontaneous combustion if not stored and monitored properly.

Are hay bales a fire hazard?

Yes, hay bales can be a fire hazard, particularly when they are improperly stored, contain moisture, and lack proper ventilation.

Is burning hay toxic?

Yes, burning hay can release potentially toxic gases and particles, which can be harmful if inhaled.

How fast will wet hay catch fire?

The time it takes for wet hay to catch fire can vary widely based on factors such as moisture content, bale size, and environmental conditions. In some cases, it can happen within a few days to a few weeks after baling, especially if conditions are conducive to spontaneous combustion.


Wet hay can catch on fire under certain conditions, primarily due to spontaneous combustion.

When hay is baled and stored improperly, with elevated moisture content and limited ventilation, microbial activity within the hay can generate heat.

If this heat is not dissipated, it can lead to the ignition of the hay. To reduce the risk of wet hay fires, it’s crucial to ensure proper drying, baling, storage, and regular monitoring to detect and address any signs of heating.