Any indoor temperature above 78∘F 𝟕𝟖∘𝐅 to 80∘F 𝟖𝟎∘𝐅 ( 25∘C 𝟐𝟓∘𝐂 to 27∘C 𝟐𝟕∘𝐂) is generally considered "too hot" for a house. Depending on what you are protecting or evaluating, the thresholds vary significantly:
It's advisable to keep your home below 80 degrees throughout the summer. A house that's too warm can be dangerous to people, pets, and the soft surfaces in your home. Set the winter temperature to 68 degrees when you're awake and 62 degrees when you're sleeping.
Here's a general breakdown of indoor temperature ranges and their potential impact: 78°F – 80°F: Generally considered warm but acceptable by many, especially if the humidity is low. This is often recommended for energy savings. 81°F – 85°F: Feels uncomfortable for most people, particularly during sedentary activities.
You might be wondering about how much external heat a person can tolerate. Live Science writes that most humans can endure about 10 minutes in 140–degree heat before suffering from hyperthermia, a lethal form of which is the aforementioned heat stroke.
How cool should my house be if it's 100 outside? Your AC can typically cool about 20°F below the outdoor temperature, so if it's 100°F outside, maintaining 78–80°F indoors is reasonable.
Many Amish homes are built with plenty of windows to help circulate the air and bring in the cooler overnight temperatures. They open the windows on the top floors to help the heat escape while the family retreats to the lower grounds within their homes for comfort.
This would put 2026 in the same range as 2023 and 2025, which according to the World Meteorological Organization (WMO) are the second and third hottest years on record to date. The WMO observed value for 2025 (1.44 ± 0.13 °C) closely aligns with ECCC's prediction for 2025 (to within 0.01 °C).
Key takeaways: The highest environmental temperature humans can survive is 104°F to 122°F (40°C to 50°C). But those temperatures aren't safe. A safe temperature range for prolonged outdoor time is 77°F to 88°F (25°C to 31°C).
Safe-to-touch temperatures are temperature standards that were established by ASTM C1055. This standard recommends that pipe surface temperatures do not exceed 140°F. Why 140°? Well, an average person can remain in contact with a 140°F surface for up to five seconds without sustaining irreversible burn damage.
Compared to hot and dry climates, the human body cannot withstand hot and humid climates nearly as well. That's because at 100 percent humidity, our sweat cannot dissipate as easily to cool our bodies down.
On average, a well-functioning air conditioner can lower the temperature in your home by one degree every hour. So if your house is sitting at 80°F and you want to bring it down to a cool 72°F, you're looking at about 8 hours.
The Short Answer Is: Yes! Lowering a thermostat by one degree can save you money on your heating or cooling bills. The exact savings depend on factors like climate, insulation, and the efficiency of your HVAC system, but it's estimated to reduce energy costs by around 1-3% per degree for each 8-hour period.
Extreme heat is also the No. 1 killer of people globally when it comes to extreme weather events.
The bedroom temperature
So here's a fun fact: in Japan, people sleep in rooms that are around 55°F (13°C) on average.
These policy recommendations are aligned with many of the goals identified in the 2022 California Extreme Heat Action Plan (EHAP). The state should consider a general maximum safe indoor air temperature of 82 degrees Fahrenheit (27.8 degrees Celsius) for residential dwelling units.
Blood clots are more likely during high heat conditions because of dehydration. While releasing sweat to cool the body and regulate temperature, you're also losing fluid that plays a vital role in circulation. “When you're dehydrated, your blood volume decreases,” said Dr. Kochar.
Humidity is Better for Your Sinuses
Extremely dry air can cause cracked lips, dry eyes, and even bloody noses. It can also aggravate any existing respiratory problems you may have like asthma or COPD.
You would exceed the IEEE P1584B standard for second-degree burns after one femtosecond in the Sun. [6] A nanosecond—the time you're spending there—is 1,000,000 femtoseconds. This does not end well for you.
Oymyakon and Verkhoyansk are the only two permanently inhabited places in the world that have recorded temperatures below −60 °C (−76 °F) for every day in January.
If your hot water temperature is set to 140 degrees Fahrenheit, it takes three seconds to burn your skin serious enough to require surgery. Three seconds isn't long at all.
Experts anticipate 2026 to be exceptionally warm, though records remain uncertain. As of May 6, 2026, Carbon Brief, which synthesizes multiple datasets and expert analyses, indicates that 2026 is likely to be the second-warmest year on record, with a 19% probability of surpassing 2024's record for the warmest year.
The Rule of 120
A helpful guideline is the "Rule of 120": if the sum of the air temperature and water temperature is less than 120 degrees Fahrenheit, you should wear thermal protection like a wetsuit or drysuit. But even this rule has limitations - always dress for the water, not the air.
By 2050, humans will be pulling 165 billion tonnes of raw materials from the Earth annually. This represents a more than 60 per cent jump from 2020. GEO-7 says the extraction of all these metals, minerals and fossil fuels will destroy many natural spaces, worsening climate change and feeding biodiversity loss.
The lowest tolerable pressure of air is about 0.47 atm (475 millibars of atmospheric pressure) - recorded at 5950m altitude. At about 0.35 atm (less than 356 millibars at around 8000m) life is impossible. Pulmonary and cerebral edema lead to death.