How to Keep Tarantulas Warm in the Winter

In the wild, tarantulas inhabit regions that experience seasonal temperature fluctuations each year. Desert and scrubland species, such as Aphonopelma from the southwestern United States and Mexico, regularly encounter winter nighttime temperatures in the 40s and occasionally the high 30s. They survive these conditions by retreating into deep burrows, where surrounding soil insulates them and maintains far more stable temperatures than the air above ground.

Grassland and dry forest species experience similar cooling cycles. During colder periods, they slow their metabolism, feed less frequently, and remain underground, where conditions are buffered from rapid temperature changes. Even rainforest species do not live in constant heat. In regions such as the Amazon Basin and the Guiana Shield, nighttime temperatures often drop into the mid to upper 60s, particularly during the rainy season. Within burrows, temperatures are even cooler and more stable.

Tarantulas are adapted to tolerate gradual cooling, but they are poorly equipped to handle dry heat, sudden hot spots, or rapid moisture loss. For this reason, overheating poses a far greater risk than mild cooling. A tarantula kept at 65°F with appropriate humidity and hydration is significantly safer than one kept at 80°F in a dry, overheated enclosure.

Why Heat Lamps, Heat Rocks, and Bottom Heaters Are Dangerous

Heat lamps, heat rocks, and bottom-mounted heat pads create intense hot spots that tarantulas cannot escape. When a tarantula needs to cool down, terrestrial species instinctively burrow deeper into the substrate, while arboreal species climb higher to take advantage of increased airflow. Bottom-mounted heat pads are especially dangerous because the deeper a terrestrial tarantula digs to escape heat, the warmer the substrate becomes. Heat lamps pose a similar risk, particularly for arboreal tarantulas, which may climb toward the top of the enclosure to escape rising temperatures, only to move closer to the heat source. These heating devices warm glass and substrate directly, turning sections of the enclosure into miniature ovens.

This causes three major problems:

Dehydration: Hot air pulls moisture out of the substrate and the spider’s body faster than it can be replaced.
Uneven temperatures: One corner of the tank may be dangerously hot while the rest remains cool, forcing the spider into stressful temperature extremes.
Burn and injury risk: Tarantulas do not sense surface heat the way mammals do. They can sit on overheated glass or substrate without realizing it's causing them harm until damage is already done.

This is why heat rocks and lamps are among the most common causes of winter losses in captive tarantulas.

Safe Ways to Keep Tarantulas Warm

The safest way to provide warmth during winter is simple: heat the air, not the spider. Warming the surrounding air raises temperatures gradually and evenly, helps maintain stable humidity, and allows the tarantula to move freely to find a comfortable zone. Directly heating the enclosure creates localized hot spots that can cause dehydration and stress.

Heat the room: Maintaining a warm room temperature is the simplest and safest option. A small space heater equipped with a thermostat and tip-over protection can gently raise ambient temperatures without creating dangerous hot spots inside enclosures. Even a slight increase can make a significant difference.

Move enclosures to warmer areas: Upper floors and smaller rooms retain heat more effectively. If enclosures are kept in cooler spaces such as basements or large living areas, relocating them upstairs during winter can help stabilize temperatures without adding new equipment.
Use insulation to trap heat: Foam board, cabinet panels, or simple insulation around shelving can reduce heat loss. Insulation does not generate heat but helps retain existing warmth.
Create a warm cabinet or microclimate: Rather than heating individual enclosures, you can warm a cabinet, closet, or shelving unit. A tall storage cabinet can be converted into a stable microclimate by installing heat tape or heat pads on the back wall and controlling them with a thermostat. Position the probe near the top center of the cabinet, add insulation, and place enclosures on shelves inside. This method warms the air within the cabinet, allowing multiple animals to benefit without the risk of burns or dehydration.
Use heat pads correctly: Heat pads can be used safely only when mounted on the side or back of an enclosure and regulated by a thermostat. This creates a gentle temperature gradient, providing both warm and cool zones while heating the air rather than the substrate. Heat pads should NEVER be placed underneath a tarantula enclosure.

What Happens When the Power Goes Out

Winter is the season when heating systems fail most often. Ice storms, blizzards, and power outages can shut down your entire setup in minutes. This is why every keeper should have a winter emergency plan.

Keep Emergency Heat Packs: Reptile shipping heat packs can provide gentle warmth for 24 to 72 hours. Keep several on hand so you can insulate enclosures in a bin or tote if the power goes out.
Have Transport Containers Ready: Large plastic totes, newspaper, paper towels, and deli cups allow you to move spiderlings, juveniles, and adults quickly and safely if relocation becomes necessary.
Know Where You Can Go: Have at least one place already arranged where your tarantulas can stay temporarily, such as a friend’s house, a family member’s home, or a workspace. Do not wait until a disaster occurs to have this conversation.

Final Thoughts

Tarantulas are ectotherms, meaning their body temperature and internal processes are controlled by the surrounding environment. They do not generate heat like humans. When temperatures rise, their metabolism increases, they move more, digest faster, and appear more active. When it cools, everything slows down. They eat less, move less, and grow more slowly. This is normal and part of their natural adaptation.

Temperature also affects their hemolymph, which functions like blood. Tarantulas rely on fluid pressure to extend their legs, so when temperatures drop and hemolymph thickens, movement feels slower and heavier. In warmer conditions, the fluid moves more freely, and their movements are smoother. This explains why spiders often seek out warmer areas in their enclosure. It is also why a tarantula may sit directly under a heat source even when it is dangerous. They are responding to temperature, not dehydration. In the wild, warm spots are typically accompanied by escape routes and stable humidity in the soil. In a glass enclosure, a heat lamp or rock creates a hot, dry area with no relief. The spider feels immediate warmth, but the environment draws moisture from its body and substrate, which can lead to dehydration, poor molts, and eventually organ failure.

Winter amplifies this problem because heated homes are already dry. Even without added heat, indoor humidity drops significantly. Using a heat lamp, heat rock, or poorly placed heat pad accelerates evaporation and dries the enclosure faster. The tarantula may be warmer, but it loses water faster than it can replace it.The goal is never to cook the spider. The goal is to maintain warm, humid air in a safe, stable range. A tarantula at 65 to 68 degrees Fahrenheit with proper humidity and a full water dish is far safer than one at 80 degrees in a dry enclosure.Once you understand this, winter care becomes much simpler. You are not fighting the cold. You are protecting your tarantula from drying out while providing enough warmth to keep it healthy.

Written by Richard from Tarantula Collective 1/12/2026