Dumeril’s Boa Temperatures, Light & Humidity Needs

dumeril's boa basking in light and uvb



Recent studies suggest that UVB is beneficial for snakes’ long-term physical and mental health. Like many snakes, Dumeril’s boas are a Ferguson Zone 2 reptile, which means that they need a UVI of 2.0-3.0 in the basking area (closest location to the UVB lamp). UVB intensity decreases with distance from the source, so your snake’s basking surface needs to be placed at an appropriate distance. If it’s too close, your snake may get “sunburned.” If it’s too far away, your snake may not be able to actually benefit from having the lamp.

ReptiFiles strongly recommends that reptile owners invest in or at least borrow a Solarmeter 6.5 to measure UVI (UV Index) for proper basking surface placement. However, if you don’t have access to a Solarmeter 6.5, here is an estimate of how far away your snake should be when basking under the UVB lamp, since UVB intensity is affected by distance.

Lamp mounted above mesh (recommended for safety):

Without mesh obstruction:

The above distance recommendations assume a ~35% mesh block. For more details on estimating basking distance based on mesh obstruction, see the Facebook group Reptile Lighting > Guides > Guide 1: Using T5-HO lamps above a Mesh Screen.

Your UVB bulb should be roughly half the length of your enclosure (ex: 34″ if the enclosure is 6′ long). It will also need to be installed in a Vivarium Electronics T5 HO or Arcadia ProT5 fixture. Optimal use distance is likely to be more variable if you use something different. 

  • Make sure your UVB fixture doesn’t have a piece of glass or plastic to “protect” the bulb. UVB rays are blocked by glass and plastic, rendering that bulb you just spent so much money on completely useless. Naked UVB bulbs are effective UVB bulbs! 

Day Length

Place your light on a timer to help your snake regulate its day/night and seasonal cycles:

  • Spring — 12 hour day
  • Summer — 13 hour day
  • Fall — 12 hour day
  • Winter — 11 hour day

Alternatively, you can sync your boa’s lights to your local sunrise/sunset times for similar results. I prefer using the Kasa Smart Power Strip to manage my reptiles’ light schedules from my phone.

Temperatures & Heating

Like all reptiles, Dumeril’s boas need a heat gradient so they can regulate their own temperature. This temperature gradient is more effectively accomplished in large enclosures than in small terrariums or tubs.

  • Basking area (ambient): 86-88°F (30-31°C)
  • Cool zone: 70-75°F (21-24°C)

Night temperatures can safely drop down to 68-75°F (21-24°C), and is actually better for the snake’s long-term health if provided. This is typically easily accomplished by turning off the heat source at night. If the snake’s enclosure is located in a particularly cool room, then it’s recommended to use a gentle source of nighttime heat such as a ceramic heat emitter or radiant heat panel, discussed later.

Measure the temperatures that your snake is feeling with a digital probe thermometer like the Zoo Med Digital Thermometer and Humidity Gauge, with the probe placed on the basking surface.

Do not use a stick-on thermometer, as these will not give you accurate results.

How to heat your Dumeril’s boa enclosure

Halogen Flood Heat Lamp

In nature, warmth comes from the sun (above), not from the ground (below). In fact, reptiles retreat underground to escape the sun and get cooler, not warmer. Providing warmth from below, as with a heat mat, is therefore unnatural and will promote unnatural behaviors. Heat lamps solve this problem by mimicking the effects of the sun and warming both the air and the ground below.

I recommend using a dual dome-style heat lamp fixture with ceramic sockets, like this one by Zoo Med. Then you will need at least two high-wattage halogen heat bulbs, such as:

The exact wattage you will need depends on the height of your enclosure and your room temperature. If it’s a little too hot, use the dimmer switch on the heat lamp to dial it down to the right level.

ReptiFiles recommends using a cluster of multiple heat bulbs in order to create a larger basking area, which will heat your snake’s body more evenly and encourage more efficient thermoregulation and healthier circulation.

  • PRO TIP: Beware “environmentally-friendly” light bulbs. These bulbs advertise a high wattage, but actually use fewer watts while maintaining the same light output as the advertised wattage. This is great for household lighting, but in a reptile enclosure you need the warmth that extra energy expenditure provides. If you can’t find a good bulb, a reptile day bulb from a pet store works, too, although it will likely have a shorter lifespan.

If you are concerned about “belly heat,” placing a piece of flagstone or slate tile under the heat lamp will absorb warmth that your snake can curl up on. In fact, I recommend doing this anyway.

Ceramic Heat Emitter (CHE)/Radiant Heat Panel (RHP)

I don’t recommend them for daytime heat, but if you need a lightless heat source for nighttime, a ceramic heat emitter is a good choice. Ceramic heat emitters produce ambient heat, also known as Infrared-C. It’s the weakest form of infrared, but it’s also the form of heat that Dumeril’s boas are most likely to encounter at night. For larger enclosures, it’s best to use a radiant heat panel instead of multiple ceramic heat emitters.

Either way, you will need to hook up each heat source to a thermostat in order to maintain safe nighttime temperatures for your Dumeril’s boa.

What about heat mats?

Under-enclosure heating devices like heat mats and heat tape are popular for use with snakes, especially terrestrial species. And they can be used, as long as they’re controlled by a thermostat. They can be particularly effective for creating a warm hiding area. However, they struggle to warm the air inside an enclosure, and produce relatively weak infrared. So I prefer to use halogen heat bulbs as my primary heat source.

CAUTION: Do not use heat rocks!

For some inane reason, heat rocks are still being sold by pet stores as a “safe” source of heat for your reptile. Though safety improvements have been made in recent years, there is still a danger of your snake getting burned. Furthermore, they’re not a good choice for heating your enclosure, as the device only warms the rock, not the surrounding air.

CAUTION: Use a lamp guard/bulb cage!

If you plan to install the heat source inside your snake’s enclosure, make sure it is surrounded by a lamp guard/cage to prevent your snake from getting burned by direct contact. (Amazon) (Arcadia)


Dumeril’s boas are native to the spiny thickets/forests of southwestern Madagascar, which are part of the xeric shrubland biome. Xeric shrublands are a type of desert that receive less than 250mm of annual rainfall. Because it receives so little rain, this part of Madagascar is considered quite dry. However, it’s not the Sahara desert and the habitat shouldn’t be treated as such.

According to experienced keepers, Dumeril’s boas do best with an average humidity between 40-60%. If you live in a moderate to high humidity area, this shouldn’t be hard to achieve. Occasional misting at night (with a pressure sprayer like this one) can be used to create humidity spikes, especially when the snake is about to shed. If you find that you’re still struggling with humidity levels, mix water into the substrate as needed for a more consistent increase in humidity.

  • PRO TIP: Use distilled water for misting (not drinking). Hard water stains are tough to get rid of, but using distilled also extends the life of your mister.

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