# The Celsius & Fahrenheit Field Guide By [Felsius](/content/site-root.html) – Updated Feb 2026 If someone texts you “it’s 68°F today” and you have to pause to figure out if that’s good news, you’ve come to the right place. ## The Basics - [Why Celsius and Fahrenheit Feel So Different](/content/learn/why-celsius-and-fahrenheit-feel-different/index.html) Numbers shape how we feel about temperature. Here's why switching can feel so tricky. - [Why Build a Weather App That Shows Celsius and Fahrenheit?](/content/learn/weather-app-celsius-fahrenheit/index.html) Switching settings can get tiresome. What it actually means to see °C and °F together. - [Why We Misjudge Temperature When Switching Units](/content/learn/why-we-misjudge-temperature/index.html) The cognitive mechanics behind anchoring errors when we convert quickly in our heads. - [Why Fahrenheit Feels More Precise (Even When It Isn't)](/content/learn/why-fahrenheit-feels-more-precise/index.html) A look at why people defend Fahrenheit, and what precision actually means in practice. ## The Feel of It - [How Hot Is 40°C, Really?](/content/learn/how-hot-is-40c/index.html) Above body temperature and into extreme territory. What actually happens at this threshold. - [How Hot Is 35°C, Really?](/content/learn/how-hot-is-35c/index.html) The step-change beyond 30°C – where heat stops being uncomfortable and starts being an argument. - [How Hot Is 30°C, Really?](/content/learn/how-hot-is-30c/index.html) Summer confusion, humidity effects, and why your Fahrenheit intuition keeps getting this one wrong. - [How Hot Is 25°C, Really?](/content/learn/how-hot-is-25c/index.html) Mild warmth calibration – why 25°C in the shade feels nothing like 25°C in direct sun. - [What Does 20°C Actually Feel Like?](/content/learn/what-does-20c-feel-like/index.html) The exact temperature that confuses most people, sitting right at the edge of jacket-or-no-jacket. - [What Is Room Temperature (and Why No One Agrees)](/content/learn/what-is-room-temperature/index.html) Science, kitchens, labs, and homes all have different answers. Here's why "room temperature" is vague by design. - [How Cold Is 10°C, Really?](/content/learn/how-cold-is-10c/index.html) Why 10°C feels colder than you expect and when a jacket stops being optional. - [How Cold Is 5°C, Really?](/content/learn/how-cold-is-5c/index.html) Properly cold – and why damp air makes it significantly harder than the number suggests. - [How Cold Is 0°C, Really?](/content/learn/how-cold-is-0c/index.html) The freezing point. What actually changes at 0°C and why some 0°C days feel much colder than others. ## Why It Matters - [Living Between Celsius and Fahrenheit](/content/learn/living-between-celsius-and-fahrenheit/index.html) For expats, travellers, and international couples – the hidden cognitive cost of a daily translation problem. - [Why Converting Temperatures All Day Is Mental Overhead](/content/learn/why-converting-temperatures-is-mental-overhead/index.html) Every conversion is a small draw on attention. Here's why that adds up more than you'd expect. - [Why Temperature Numbers Don't Map Cleanly to Comfort](/content/learn/why-temperature-numbers-dont-map-to-comfort/index.html) The same number feels different based on humidity, wind, and what you've been calibrated to. Here's why. - [Why "Feels Like" Temperature Often Makes Things Worse](/content/learn/why-feels-like-temperature-makes-things-worse/index.html) The apparent temperature metric sounds helpful but often just adds confusion. Here's what it actually measures. - [Why Americans Struggle With Celsius (and Why That's Normal)](/content/learn/why-americans-struggle-with-celsius/index.html) It's not ignorance – it's how temperature intuition actually works. A fair-minded look at the switch. - [Why Most Weather Apps Make Temperature Harder Than It Needs to Be](/content/learn/why-weather-apps-make-temperature-harder/index.html) The single-country assumption baked into most apps – and what a different design looks like. ## Curiosities - [Why −40° Is the Same in Celsius and Fahrenheit](/content/learn/why-negative-40-is-the-same/index.html) The one point where both scales meet. It's easier to understand than you'd think. ## Interactive Tools - [The What to Wear Temperature Guide](/content/learn/what-to-wear/index.html) Does 15°C mean t-shirt weather or mild hypothermia? Use our interactive guide. This Field Guide is written by the team behind [Felsius](/content/site-root.html). Felsius is the weather app that shows Celsius and Fahrenheit together. Never google "what's 68°F in °C?" again Felsius shows °C and °F together. No switching. No converting. Instant clarity.