Does a Humid Climate Affect Dehydrating Food

humid climate dehydrating

Dehydrators are becoming very popular in the home these days and it is little wonder why. Drying food in your own home can save money and will prolong the viability of food that you have grown in your garden.

We don’t all have the same climate though, and as we personally live in a tropical climate we can tell you with certainty that a Humid Climate has a huge effect on Food Dehydration.

In this article we explain why it happens and how it might affect you and finally, how we personally get around the potential problems safely.

How Food Drying works

Drying or dehydrating is a very old process with many prior generations of people having using this technique to store food for later use. In simple terms, dehydrating is the process where moisture is removed from a food.

It can be used with fruits, meats, seeds, and more. The modern process involves benchtop cabinets or alternatively stackable trays that are filled with moist food. Some people have asked if all the trays need to be in the machine when you use it, and we have an article that addresses this. It is titled “Do I have to use all the trays in a dehydrator?

Warm dry air is introduced and passed over this food via a fan that pushes air passed a heating element and this air then vents to the outside of the cabinet or tray stack.

The moisture from the food surface will be transferred to the warm introduced air and expelled from the machine via the fan-forced airflow.

a stack of dehydrating rings
Humidity can be a challenge when dehydrating fruit.

How Weather Changes the drying process

The air around us contains moisture, and all air has an ultimate limited capacity to hold that moisture.

The food dehydration process depends on this same air to have some available capacity to accept the removed moisture from the food.

A dry climate will have air that has a lot of capacity to accept moisture whereas a humid climate will have less available capacity to accept food moisture.

This is because the air is already carrying far more moisture than the dry climate air does due to the relative humidity of the the air in that area.

The amount of moisture in the air at any particular location will be different to other locations and the air can differ from outdoors to indoors if air conditioners are involved.

All of this will affect the efficiency of your dehydrator from day to day, and season to season.

What is the Best Season for Food Dehydrating

The best season to safely dehydrate food is the time of year when the relative humidity is at its lowest for the year in your area.

The seasonal changes in relative humidity can be found in weather maps for your continent and state.

Tropical zones are often humid most of the year.

Sub-tropical zones often have a drier winter than the summer.

Temperate and Mediterranean climates usually have a drier summer and a wetter winter. You know your seasons where you live.

papaya ready to dry
Home grown produce ready for the dehydrator.

Potential Problems with Food Dehydrating in rainy weather.

There is a range of temperatures and climatic conditions where the process of dehydrating food operates most effectively.

Rain is associated with humidity and it can be a short lived event within a typically dry season or it can be a defined wet season like we have here just below the Daintree national park in Qld, Australia.

The potential problems that you will face while dehydrating food in rainy weather are primarily bacteria, mold, and fungus spores (yeasts) that are all throughout the natural environment.

These cannot be removed without expensive filtration systems and processes and we won’t go into these here.

You might think that the way to overcome these potential problems is to regulate the temperature of the air higher as it enters the dehydrator.

Most machines have dials that allow for temperature adjustment.

The risk to raising the temperature in the dehydrator is the outer surface of the food can dry and harden before the internal moisture has had time to be extracted.

It is similar to cooking the outside of the food and having the food uncooked inside.

The best way to operate your dehydrating machine in high humidity is to increase the air movement instead of raising the temperature.

As the air is already humid before it enters the machine, it can only take on a little of the moisture from the food so by replacing the loaded air more often it will help alleviate some of the rainy weather hazards.

Alternatives to dehydrate food in humid conditions.

An alternative to drying your food in the dehydrator is to use an oven that you would typically use for baking and cooking full meals.

These often are fan-forced and will dry the air enough to serve the purpose. The big downside of this is the oven is taken up for extended amounts of time and the cost of running the oven will be far higher than a dedicated food dehydrator.

The oven may not allow for a low enough temperature to dehydrate food, and will only allow cooking. It is a sub-optimal method for safety reasons as well.

You might want to run the oven with the door ajar and this will work but it introduces hot air into the room and can create hot items nearby for little fingers to grab and touch.

The next alternative is to possibly freeze the product you wish to dry until the season changes to a less humid time of the year. This will depend on the type of food you are working with, and whether freezing will damage the product for future drying.

We have a different alternative here on our property. It is a cob oven that is fed with a rocket stove base.

cob oven internals
This oven can dry a lot of produce if needed.

We use this to dry foods when the humidity is too high for the stacked tray dehydrators we have. This works well because the air in the oven has been dried from the fire.

We have a detailed article on using cob ovens as dehydrators and the things to be aware of. It is titled “Can a cob oven dehydrate food?“.

The downside is there is a smoky taste to the food after it has dried but this is a benefit with some foods. If you are interested in the process we have an article titled “using a cob oven, 11 questions answered“.


Food can be dried in most climates but the hardest is in the tropics where the atmosphere can sometimes hold more water vapor that the food you want to dry.

Article by Tim Blanch for He is a qualified Permaculture designer.