How the Weather and Humidity Affects Candy Making

The weather affects our lives in so many ways. Think of how much harder it is to get to work done during a snowstorm or torrential downpour – and doesn’t everyone seem to be in a much better mood on a bright, sunny day than when it’s dark and gloomy outside? Believe it or not, the weather and humidity can also play a prominent role in the process of making candy, as it can have a dramatic impact on the quality of the finished product.

How the weather and humidity affects candy making

Issues with Candy Making in High Humidity

Humidity doesn’t just cause bad hair days – it can also lead to bad candy making days as well! Think of how sticky the air feels on days when the humidity is high. You may also feel a stickiness on hardened sugar you are using for making candy. Cooking candy sugar to the proper temperature requires achieving the appropriate sugar-moisture balance. High humidity hastens the breakdown of sugar as it cools. Once the candy has cooled to the point where it can no longer evaporate moisture, it can actually begin to reabsorb moisture. This produces a softer product than may be desirable.

For best results, restrict candy making to days when the relative humidity is below 35 percent. If you don’t happen to have a hygrometer handy, you can usually learn the current relative humidity from a local news broadcast or telecast, or by checking one of the many weather sites online. As a rule of thumb, only make candy when the weather is cool and dry, as the candy will cool faster and reduce the likelihood of crystal formation. Remember, high-humidity days can occur during the winter as well as summer.

Check the Barometric Pressure Prior to Making Candy

A drop in barometric pressure can also negatively impact the candy-making process, particularly at high altitudes. Because the air pressure at higher altitudes is much lower than at sea level, it lowers the boiling point of water. This will have a direct effect on how quickly water in syrup evaporates during candy making. Even if you are cooking at sea level, the presence of low-pressure weather systems can replicate the effects of high altitude conditions.


While most people do not have barometers outside their homes to measure atmospheric pressure these days, you can always check your local weather forecast to determine if the pressure is rising, dropping or remaining constant. Typically, the drop in barometric pressure coincides with the arrival of bad weather, just another reason why you should restrict candy making to good-weather days.

Weather-Related Candy Making Tips

If you must make candy during periods of high humidity, a dehumidifier can remove much of the excess moisture from the room. It also helps to run the air conditioning at a lower temperature. Additionally, allowing sugar to dry in an airtight container with an effective desiccant (drying agent) for a few hours can promote the absorption of excess moisture that leads to soft candy.

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