Venus is the hottest planet in the solar system, with a surface temperature that hovers around 465 °C (roughly 870 °F). That is hot enough to melt lead and zinc, and it stays that way around the clock, on both the day and night sides. The planet manages this despite being farther from the Sun than Mercury, because its dense carbon-dioxide atmosphere traps heat with brutal efficiency. What makes Venus’s heat so remarkable is not just the number but how consistent, how inescapable, and how alien it truly is.
What the Numbers Actually Are
The average surface temperature on Venus sits at about 740 kelvins, which translates to roughly 467 °C or 872 °F. The atmospheric pressure at ground level is around 91 times Earth’s, which is equivalent to the pressure you would feel nearly a kilometer underwater in Earth’s oceans. These readings were first confirmed by Soviet Venera landers in the 1970s and 1980s, and they have held up across every subsequent measurement and model. For context, your kitchen oven maxes out somewhere around 260 °C on a high broil setting. Venus’s surface runs at nearly double that, all the time.
What makes this temperature surprising is that Venus actually absorbs less sunlight per square meter than Earth does. The thick sulfuric-acid clouds blanketing the planet reflect about 80 percent of incoming sunlight back into space, giving Venus an extremely high albedo. If reflected sunlight were the whole story, the surface would be cold. The heat comes almost entirely from below those clouds, where the greenhouse mechanism does its work.
Why Venus Is Hotter Than Mercury
Mercury orbits much closer to the Sun but has no meaningful atmosphere to speak of. Sunlight hits its surface full force and heats the dayside to around 430 °C, but the nightside plunges to roughly −180 °C because there is nothing to hold the heat. Venus, nearly twice as far from the Sun, beats Mercury’s dayside temperature and then keeps that temperature through its night, which lasts about 58 Earth-days due to its painfully slow rotation.
The difference is entirely atmospheric. Venus’s atmosphere is about 96.5 percent carbon dioxide, a greenhouse gas that absorbs infrared radiation radiated upward from the surface and re-emits it back down. Because the atmosphere is so thick and so rich in CO₂, infrared photons cannot escape easily. They bounce around, heating the gas and the surface in a feedback loop. This is the same basic mechanism that warms Earth by about 33 °C above what its temperature would otherwise be, but on Venus the effect is cranked up to an extreme. The carbon dioxide is supplemented by trace amounts of water vapor and sulfur dioxide, both of which absorb infrared light at slightly different wavelengths, plugging additional gaps through which heat might otherwise escape.
The Runaway Greenhouse and How Venus Got This Way
Venus was not always this hot. Modeling work on runaway greenhouse atmospheres has shown that if the solar energy hitting a planet exceeds a critical threshold, surface water begins evaporating faster than it can condense, adding more and more water vapor to the atmosphere. Water vapor is itself a potent greenhouse gas, so each increment of evaporation raises the temperature further, which evaporates more water, and the cycle feeds on itself. For cloud-free, fully saturated conditions, the critical solar flux at which this runaway occurs is about 1.4 times the current solar energy flux at Earth’s orbit.1PubMed. Runaway and moist greenhouse atmospheres and the evolution of Earth and Venus Venus, being closer to the Sun, exceeded that threshold early in its history.
There is evidence that Venus may originally have had liquid water oceans, particularly if its initial water endowment was similar to Earth’s. Cloud cover on a warm, wet planet can temporarily depress surface temperatures by reflecting sunlight, which could have kept conditions habitable for a time. But Venus lost those oceans because water vapor in the upper atmosphere was broken apart by ultraviolet sunlight, and the freed hydrogen escaped to space.1PubMed. Runaway and moist greenhouse atmospheres and the evolution of Earth and Venus Without water to cycle through geology and pull carbon dioxide out of the air (as happens on Earth through weathering and ocean absorption), CO₂ accumulated in the atmosphere with no exit. The result is the atmosphere Venus has today: a massive blanket of carbon dioxide that traps heat relentlessly.
If the runaway had gone even further and Venus had retained a full ocean’s worth of water vapor in its atmosphere, the surface temperature could have exceeded 1,500 K, which is above the melting point of silicate rock.2Icarus. Runaway and moist greenhouse atmospheres and the evolution of Earth and Venus That did not happen because the hydrogen escaped, but it gives a sense of how powerful a runaway greenhouse can be in theory.
Almost No Day-Night Temperature Difference
On Earth, nights cool off and winters bring lower temperatures because the atmosphere is thin enough to let heat radiate away relatively quickly. Venus has the opposite situation. The atmosphere is so massive and opaque to infrared radiation that the surface temperature barely budges between the sun-facing and space-facing hemispheres. Measurements from orbit and from landers show only a few degrees of variation at most, which is remarkable given that a single Venusian day (one full rotation) takes about 243 Earth-days. You might expect the nightside to cool significantly during that long stretch of darkness, but the atmosphere’s thermal inertia is simply too large.
Part of the reason for this uniformity is atmospheric circulation. Venus’s atmosphere rotates far faster than its surface, a phenomenon called super-rotation. At the cloud-top level, the atmosphere whips around the planet in roughly four Earth-days, about 60 times faster than the planet itself rotates. Research using data from the Japanese Akatsuki orbiter has shown that this super-rotation is maintained by a combination of thermal tides and atmospheric waves, which transport energy and angular momentum around the planet.3Science. How waves and turbulence maintain the super-rotation of Venus’ atmosphere This rapid circulation distributes heat from the dayside to the nightside efficiently, smoothing out temperature contrasts that would otherwise develop.
Altitude and the Few Places Where Temperature Varies
While the surface temperature is famously uniform across latitudes and longitudes, elevation does make a difference. Venus has significant topography, including highland plateaus like Ishtar Terra and volcanic peaks like Maxwell Montes, which rises about 11 kilometers above the mean surface. At higher elevations, the atmosphere is slightly thinner and temperatures drop, following the same basic principle that makes mountaintops colder on Earth, though the details differ because Venus’s atmosphere is so much denser.
The temperature gradient in Venus’s lower atmosphere is roughly 8 °C per kilometer of altitude, so the highest peaks can be around 80–90 °C cooler than the lowland plains. That still leaves them at hundreds of degrees, but the difference has real consequences. At those slightly lower temperatures, compounds that are gaseous in the lowlands can condense. Chemical equilibrium modeling has shown that lead sulfide (galena), bismuth sulfide, and related metal compounds are expected to condense on the Venusian highlands.4Icarus. Heavy metal frost on Venus Radar observations from the Magellan orbiter detected unusually low radar emissivities on highland surfaces, and this metallic frost is the leading explanation. Venus’s mountaintops may literally be dusted with a thin coating of metallic snow.
Weather Near the Ground
Even in the dense, scorching lower atmosphere, there is something resembling weather. The planetary boundary layer, the turbulent zone just above the surface where the ground’s heat drives convection, behaves differently depending on elevation and time of day. Modeling of Venus’s boundary layer dynamics has found striking differences between highland and lowland locations. Over high terrain at midday, the convective boundary layer can extend up to 7 kilometers above the local surface, with vertical wind speeds reaching about 1.3 meters per second. At midnight over the same terrain, convection barely extends half a kilometer, and vertical winds drop below 0.2 meters per second.5Icarus. Venus boundary layer dynamics: Eolian transport and convective vortex
Over low plains, the convective layer at noon is much shallower, reaching only about 2 kilometers despite similar surface heating. The reason is that large-scale atmospheric dynamics at low elevations push downward and suppress convection, while at higher altitudes those same dynamics push upward, feeding energy into the boundary layer and creating a much deeper zone of turbulence.5Icarus. Venus boundary layer dynamics: Eolian transport and convective vortex This means the near-surface environment is not identical everywhere, even if the temperature readings at the ground are broadly similar. Wind patterns, dust transport, and convective activity all vary with terrain.
The Freezing Upper Atmosphere
One of the stranger facts about Venus is that while the surface bakes at 465 °C, the upper reaches of its atmosphere are extraordinarily cold. The mesosphere, roughly 80 to 120 kilometers above the surface, can plunge to temperatures far below anything found on Earth’s surface. Modeling and satellite observations have shown that temperatures in Venus’s upper mesosphere can drop below about 90 K, which is around −183 °C. At those temperatures, both water and carbon dioxide can condense into solid particles, forming ephemeral ice clouds of CO₂ nucleating onto water ice.6Journal of Geophysical Research: Planets. Ephemeral Ice Clouds in the Upper Mesosphere of Venus
So Venus has a vertical temperature swing of more than 600 °C from surface to upper atmosphere. The surface sits above the melting point of several metals; the high atmosphere is cold enough for dry ice. This gradient is far steeper than on any other rocky planet in the solar system, and it exists because the thick lower atmosphere traps heat so effectively while the thin upper atmosphere radiates freely to space.
What Spacecraft Experience on the Surface
The temperature on Venus is not just an abstract number. It has very concrete engineering consequences. The Soviet Venera program sent a series of landers to the Venusian surface between 1970 and 1985, and later the Vega-2 lander followed. Despite carrying substantial insulation, phase-change cooling materials, and other heat sinks to protect their batteries and electronics, none of these missions survived more than about two hours after reaching the surface.7ECS Meeting Abstracts. High Temperature Batteries for Venus Surface Missions The heat simply overwhelmed every thermal-protection strategy available at the time.
This remains one of the central challenges for future Venus exploration. Modern mission concepts, including NASA’s proposed DAVINCI and VERITAS missions and ESA’s EnVision, focus primarily on orbital or atmospheric measurements for exactly this reason. A lander that could survive days or weeks on the surface would need electronics built from materials like silicon carbide that can operate at Venus temperatures, and batteries designed from scratch for extreme heat. Research into high-temperature batteries is ongoing, but we are still far from a long-lived surface station.
How Venus Handles Its Internal Heat
The temperature story on Venus is not only about what the Sun and atmosphere do. Like Earth, Venus generates internal heat from radioactive decay of elements in its rocky interior. But the way that heat gets to the surface is strikingly different. Earth loses most of its internal heat through plate tectonics, where oceanic crust is created at mid-ocean ridges and destroyed at subduction zones. Venus does not appear to have plate tectonics in the same sense.
Recent analysis of Venus’s lithosphere strength and heat flow suggests the planet’s average surface heat flow is about 31 milliwatts per square meter, with higher values along rift systems that resemble active tectonic zones on Earth. The total heat loss is estimated at 11 to 17 terawatts, which is comparable to the total heat produced by radioactive decay in Venus’s interior.8Communications Earth & Environment. Heat loss and internal dynamics of Venus from lithosphere strength In contrast, Earth loses considerably more heat than it produces through radioactivity alone, because plate tectonics efficiently moves hot material from depth. Venus, without that conveyor belt, dissipates proportionally much less of its internal heat budget.
This has implications for volcanism. If Venus cannot shed heat through steady plate recycling, the heat may build up until it escapes through episodic volcanic resurfacing events, which some researchers have proposed to explain Venus’s relatively young-looking surface (few impact craters, suggesting it was repaved by lava a few hundred million years ago). Those volcanic eruptions would also pump more CO₂ and sulfur compounds into the atmosphere, potentially reinforcing the greenhouse effect from below.
How We Measure Venus’s Temperature From Afar
You might wonder how scientists know the surface temperature so precisely when it is hidden beneath kilometers of opaque cloud. The answer involves a combination of direct measurement and remote sensing. The Venera landers carried thermometers and barometers that took readings all the way down through the atmosphere, giving us a detailed vertical temperature profile from the cloud tops to the ground. Those readings established the baseline.
From orbit, instruments can peer through narrow infrared windows in the atmosphere, wavelengths at which the CO₂ and clouds are slightly less opaque, to detect thermal radiation coming from the lower atmosphere and surface. The VIRTIS instrument on ESA’s Venus Express spacecraft mapped the planet’s nightside thermal emissions through infrared windows centered around 1.74 and 2.25 micrometers. These maps reveal spatial variations in cloud opacity in the lower cloud deck, around 44 to 48 kilometers altitude, and provide indirect information about cloud particle sizes and the thermal state of the deep atmosphere.9Icarus. Global maps of Venus nightside mean infrared thermal emissions obtained by VIRTIS on Venus Express Combined with the direct lander data, these observations give scientists confidence that the surface temperature is well characterized even though we cannot see the ground directly.
Venus as a Greenhouse Cautionary Tale
Venus often appears in discussions about climate change on Earth, sometimes as a worst-case analogy. The comparison is imperfect but instructive. Earth is not about to undergo a runaway greenhouse; the solar flux at our orbit is below the critical threshold needed to trigger that kind of irreversible ocean evaporation, and our CO₂ levels, while rising dangerously, are orders of magnitude below Venus’s atmosphere. The relevance of Venus is less as a direct prediction and more as a demonstration of how far atmospheric composition can push a planet’s surface temperature away from what its distance from the Sun alone would dictate.
Venus receives about 40 percent less solar energy per square meter than Mercury, yet is hotter. It reflects far more sunlight than Earth, yet is hotter. What matters is not how much energy arrives but how easily it can leave. On Venus, it effectively cannot leave. The atmosphere is so opaque in the infrared that the surface must reach extreme temperatures before enough thermal radiation manages to fight its way upward through the CO₂ and out into space to balance the incoming solar energy that does get absorbed. That equilibrium point happens to be 465 °C. If you removed the atmosphere tomorrow, Venus’s surface temperature would plummet to something much more moderate within a geologically short time. The heat is not coming from the Sun directly; it is a product of the atmosphere’s refusal to let heat go.