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How Long Can A Turtle Survive Without A Heat Lamp?

Are you curious about what you’d need to own a pet turtle? Or maybe your turtle’s heat lamp has blown, and you’re worried about how long your turtle can survive without it.

Most adult turtles can survive without a heat lamp, but they won’t be healthy. And hatchlings and young turtles need a heat source to survive. 

So, if you’re a new turtle owner or a veteran without a working heat lamp, you can be confident that your pet will be safe for a while until you get a new one sorted. 

Everyone knows that reptiles like snakes and lizards need heat to survive, but why do turtles? 

Why Do Turtles Need Heat Lamps?

Turtles, like most reptiles, are ectothermic. They rely on external sources to help keep their internal temperature regular. That’s why many reptiles are found in hotter climates. 

Without the correct ambient temperature for their needs, turtles will lose their appetite, and their immune systems will weaken. And, cause them to contract a whole host of diseases. 

As with many reptiles, turtles can survive without a heat lamp (or source) for periods while remaining healthy. Many climates in which wild turtles live have fluctuating seasons, and they adapt to these harsher conditions in many different ways, including brumation and, for aquatic turtles, spending most of their time underwater.  

But, with all species, there is a limit to how cold a turtle can survive without having lasting health problems. So, what is that temperature? 

Coldest Temperature Turtles Can Survive

What extreme cold temperature a turtle can survive under depends on the species, health condition, and how long they’re subjected to the low temperature. 

Here is a sample selection of common pet species and their cold temperature limits.

Species Temperature (ºF)
Painted Turtle<37
Box Turtle<41
Sulcata Turtle<45
Red-eared Slider<50
Tortoise <38

As you can see, temperatures below 50ºF are entering the range of being too cold for many popular turtle species. If the turtle’s enclosure drops to 50ºF or below, you’ll see brumation behavior like slow movements and burrowing (depending on the turtle). 

What Lamp Does Your Turtle Species Need?

With the importance of heat for maintaining your turtle’s health and happiness, the next question is what type of heat lamp suits your pet the best. 

Again, it will depend on the turtle species, but it’s important to know what basking temperature each species needs.

Basking Temperatures

Generally, turtles need a basking temperature of 80-90ºF to remain healthy. With some species, there are slight temperature differences:

Species Basking Temperature (ºF)
Red-eared Slider80-90
Map turtle80-90
Box turtle85-90
Mud turtle85-95

Along with having the correct basking temperature, it’s essential that you keep your turtle’s basking spot 10 degrees warmer than its water.

And, if your turtle is unwell, you may need to raise the tank’s temperature to help offset fever symptoms. 

If you’re unsure what temperature suits your turtle best, talk with your vet first.  

Wattage Needs 

Trying to decide what bulb wattage your turtle’s tank needs can be mind-boggling, but the following three things will help you pick the right type. 

  1. The size of the basking area,
  2. the number of turtles, and
  3. the size of the turtles. 

Generally speaking, the bigger the basking area and the number of turtles, the higher the wattage needs to be. 

For example, if you only have one turtle with a small basking space, a 50-watt bulb is perfect. Whereas, if you have three large turtles and a big basking area, a 100-watt bulb is a great choice. 

It’s important to keep in mind that with each increase in wattage, so does the distance from the basking area. So, the best placement for each bulb’s wattage is:

  • 6-8 inches from the basking area for 50-watt bulbs,
  • 7-9 inches for 75-watt bulbs,
  • 9-11 inches for 100-watt bulbs, and
  • 11-14 inches for 100+ watt bulbs.

How Hot Is Too Hot?

With more wattage comes more heat. And, although turtles are robust creatures, they can get burnt. If a turtle’s basking spot is too hot, it risks burning its belly while resting on the surface.

The basking temperature for most turtle species tops out at 90-95ºF, but it’s essential to make sure the tank’s ambient temperature stays around 72-77ºF to keep the turtle content. 

Again, some species, like the Yellow-Bellied Slider, can be happy in tanks measuring 80ºF but do best in temperatures in the high 70s. 

The Importance of UVA/UVB Light

When searching for the perfect bulb, pick a UVB light. And make sure that it produces UVB light rather than just being named UVB. 

There is a debate amongst herpetologists on the importance of UVA light for turtles. But there is a consensus that it helps maintain a good activity level and breeding.

Whereas UVB light is crucial for turtles. This light promotes bone growth, bone strength, bodily functions, and keeping a strong shell. 

Without this vital light, your turtle will be vulnerable to sickness, bone weakness, and shell malformation.  

How Long Should The Heat Lamp Be On For?

Heat and UVB lamps aim to mimic the turtle’s natural environment. So, ideally, there should be light and heat from dawn to dusk, around 10-12 hours per day. 

Heat Lamp During The Night?

Knowing that turtles are ectothermic can cause concern about whether they need a heat source 24/7, but this isn’t the case. Again, it’s all about mimicking their natural environment, so a night temperature dip is normal.

As long as your turtle gets enough UVB and heat throughout the day, there’s no need to keep the heat lamp on at night. 

Heat Lamp During The Summer?

If you live in a hot summer climate, you might wonder if you need to use a heat lamp for your turtle. The simple answer is yes. 

Most homes during the summer are air-conditioned, so the likelihood of the temperature within the tank being high enough is extremely slim. Plus, turtles need the option to be able to move in and out of their basking area to prevent overheating.

But, because of the increased surrounding temperature, there is a good chance that the heat lamp doesn’t need to be on as long to maintain the tank’s temperature.  

How To Care For Your Turtle With Alternative Heat Sources

There is nothing as effective at maintaining your turtle’s needs than a heat lamp, but there may be different reasons why a heat lamp just isn’t possible. It may not be available in your area, or it’s out of your budget for the moment. 

Luckily, you can choose from a few alternative heat sources to keep your pet healthy. Though, it’s crucial to seek advice from your vet or turtle specialist before choosing a heat alternative. 

Ceramic Heating Emitters

Ceramic heat emitters (CHEs) differ from traditional heat lamps as they provide heat without a light source. 

These CHEs are placed within the enclosure and can replace a basking heat lamp. However, it shouldn’t be used to heat the whole tank. 

Made of ceramic, these emitters are a constant source of warmth to your turtle without the risk of burning them or a fire breaking out. 

Mercury Vapor Bulbs

Mercury vapor lamps are three-in-one lamps providing heat, visible light, and UV light. Instead of getting two separate lamps, this type of lamp can be a cheaper solution.

These lamps are best suited as basking lamps as the UV and heat are strongest directly underneath them. Mercury vapor bulbs emit higher UV light than is needed, which can be a perfect choice if the turtle tank is tall.

However, it’s important to note that too much UVB can damage your turtle’s eyes, so placement is key. 

Also, these bulbs get very hot and don’t work with lamp dimmers, so if you have a tiny tank or can’t find the correct wattage that won’t overheat the tank, it’s best to avoid them. 

Plus, because of the heat mercury vapor bulbs emit, you’ll want to avoid plugging it into a plastic socket to prevent fire hazards. 

Under-Tank Heater/Heating Pad

Although it’s not the safest heat alternative, an under-tank heater/pad may suit if you’re in a pinch. Under-tank heaters and heating pads sit under the enclosure and permeate heat through the tank floor.

The problem is that turtles have a thin plastron (belly), and, with heat coming from underneath, they are at risk of being burnt and overheating. 

Also, finding the balance of sufficient temperature without hurting your turtle is extremely difficult with under-tank heaters and heating pads. Hence, why they’re not a recommended heat source. 


Although turtles are capable of surviving without a heat lamp, it’s crucial to their health that they get plenty of heat throughout their day. This heat enables turtles to be as active as they want, maintain good health, and stay comfortably warm. 

Even with different heat source alternatives, the best source is a heat lamp. It provides heat overhead without risking the turtle’s plastron burning.

But, if budget or availability doesn’t allow for that, mercury vapor bulbs can be the smartest and most cost-effective option for your turtle’s well-being.