Pottery clay responds dramatically to changes in temperature and humidity. High moisture in the air can make clay sticky, slow drying, and encourage mold growth, while dry or cold conditions may lead to cracking, uneven shrinkage, or weakened structure. Storing clay properly, adjusting your workspace conditions, and timing your projects with the weather in mind can help ensure consistent results and fewer problems throughout the year.
Whether you’re throwing on the wheel in a climate-controlled studio or hand-building in your garage, weather plays a bigger role in your pottery practice than you might think. Humidity, temperature shifts, and even the time of year can alter how your clay behaves. Understanding these environmental effects can help you avoid frustrating setbacks and adapt your workflow for better results year-round.
Moisture in the Air: The Role of Humidity
Humidity is one of the most critical weather factors influencing clay. Since clay is porous and full of water, it constantly exchanges moisture with the surrounding environment. High or low humidity can change how long your pieces take to dry and how evenly they do it.
High Humidity Conditions
If you’re working in a humid environment (think summer in the Southeast or a rainy coastal climate), your clay will dry more slowly. At first, that might sound like a good thing. After all, slow drying reduces the risk of cracks. But extreme humidity can lead to problems like:
- Uneven drying: Exposed areas (like rims or handles) may dry faster than thick bases, leading to internal stress.
- Mold growth: Damp storage conditions can cause mold to grow on clay, tools, or bisque pieces.
- Delayed glazing timelines: Pieces take longer to reach the bone-dry stage, delaying bisque firing and workflow.
To counter these issues, increase airflow in your workspace with fans or dehumidifiers, and avoid stacking damp pieces too closely together. If mold forms on clay in storage, a quick misting of vinegar water can neutralize it without harming the material.
Low Humidity Conditions
In dry weather, especially during winter when indoor heating pulls moisture from the air, clay can dry out too quickly. This rapid drying causes:
- Cracking during drying
- Difficulty joining pieces
- Shorter working time on the wheel or table
To slow things down, loosely cover pieces with plastic, wrap handles and joints with damp paper towels, or store clay in a damp box. Misting the air or using a humidifier can help stabilize the environment in arid conditions.
Temperature Swings and Clay Performance
Air temperature also has a strong influence on clay behavior, especially when paired with humidity.
- In hot conditions, water in the clay evaporates faster, shortening working time and increasing the chance of warping or cracking if pieces dry unevenly.
- In cold conditions, especially near freezing, the water in clay can freeze, expanding and damaging its internal structure.
Never leave damp clay outdoors or in unheated areas during freezing temperatures. If clay has frozen, allow it to thaw completely and re-wedge thoroughly to restore workability. Be aware, though, that some batches may be permanently compromised.
Practical Tip:
If you’re firing in a garage or shed studio during the winter, give your bisqueware extra time to reach room temperature before firing. Sudden temperature jumps from cold to hot can cause thermal shock, even in bone-dry pieces.
Seasonal Storage Considerations
When storing clay long-term, seasonal weather changes can degrade its condition if not properly managed. Heat can dry out your clay and harden bags into bricks; cold can freeze it and cause expansion cracks. Humid conditions can encourage bacterial or mold growth in unsealed containers.
To store clay safely year-round:
- Use airtight containers or tightly sealed bags.
- Keep it in a climate-controlled space when possible.
- Rewedge older clay before use, especially if stored for months.
Clay that’s too stiff from drying out can usually be rehydrated by adding water and sealing it in plastic for a few days. However, clay that smells intensely sour or shows black spots may be contaminated or moldy and should be discarded.
Drying: Timing Is Everything
Drying is one of the most sensitive stages of pottery, and weather can make it unpredictable. Summer heat and winter dryness can both accelerate drying unevenly, especially for wide, flat forms like plates or trays. Sudden drying changes often lead to cracks or warping.
To encourage even, weather-resistant drying:
- Cover pieces loosely with plastic overnight and slowly uncover over several days
- Dry larger forms upside down when possible to prevent curling
- Use a damp box or closed cabinet to slow down the process in dry seasons
These strategies give the moisture inside the clay more time to migrate outward, reducing internal stress and preserving your hard work.
Outdoor Firings and Atmospheric Effects
If you’re doing raku, pit firing, or any other outdoor process, weather matters even more. Wind, rain, and rapid temperature changes can completely derail a firing session or create unexpected effects on your glazes.
Be mindful of:
- Wind: Can steal heat from your kiln and cause inconsistent temperatures.
- Rain or snow: Can damage freshly fired or still-hot pieces, causing them to crack.
- Humidity: May influence the reduction atmospheres or the glaze surface quality.
If you’re planning an outdoor firing, check the forecast carefully. Even a sunny day can cause problems if high winds push too much oxygen into the chamber or interfere with your fuel source.
Kiln Room Conditions
Even indoor kilns are not immune to environmental changes. The room’s ambient temperature and humidity can affect the efficiency of your kiln and the behavior of glazes.
- A humid kiln room may extend cooling times and affect the glaze surface.
- A hot kiln room in summer may require more ventilation or airflow for safety.
- Clay stored in a hot, dry kiln room may begin to dry before you’re ready to use it.
For optimal results, try to maintain a stable environment in your kiln space year-round. Use thermometers and hygrometers to monitor conditions and adjust fans, vents, or climate control systems as needed.
Pottery is both an art and a science, and weather brings a variable you can’t always control, but you can adapt. Whether it’s slowing down the drying process during a winter cold snap or fighting off summer humidity with airflow and spacing, minor adjustments can make a big difference. Being aware of how climate affects your clay will help you create more consistent, crack-free, and beautifully finished pieces all year long.
Need Weather-Smart Pottery Tools or Clay?
Call Clay King at 888-838-3625 or email info@clay-king.com. We carry a wide range of clays, tools, and drying solutions to help you work confidently in any climate—and our team is always happy to answer your questions.
Our team can guide you to the perfect match for your goals, firing schedule, and skill level.
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