The United States, Myanmar, and the Cayman Islands share something the rest of the world has moved past: the Fahrenheit scale. While nearly every country on Earth gives weather forecasts in Celsius, Americans describe sweltering July days as "95 degrees" — a number that would sound arctic in Europe, where 95°F is a civilizational crisis at 35°C.

Who Invented Fahrenheit, and Why?

Daniel Gabriel Fahrenheit, a German-Dutch physicist, proposed his scale in 1724. He set 0°F as the coldest temperature he could reliably reproduce — a brine of ice, water, and ammonium chloride — and 96°F as normal human body temperature. (The modern value is 98.6°F; the slight drift came from later calibration.) The scale was practical for weather and medicine in the context of 18th-century European meteorology.

Anders Celsius proposed his scale in 1742, and it was immediately more elegant: 0° for the freezing point of water, 100° for boiling. The Celsius scale aligned with the logical underpinning of the later metric system, making it the natural choice for scientific use.

Why Did the US Never Switch?

The Metric Conversion Act of 1975 actually mandated a voluntary transition to the metric system in the United States — including, theoretically, Celsius. The federal agency created to oversee this (the U.S. Metric Board) was defunded in 1982 under the Reagan administration. "Voluntary" metrication stalled entirely.

Several factors entrenched Fahrenheit specifically:

  • Infrastructure inertia: Ovens, thermostats, building codes, and medical equipment across millions of buildings were calibrated in Fahrenheit.
  • Human intuition: For weather purposes, Fahrenheit's 0–100 range maps well to "very cold → very hot" for the continental US climate, making it psychologically intuitive to Americans even if arbitrary to everyone else.
  • Cultural identity: Celsius feels foreign to anyone who grew up in Fahrenheit, and vice versa. Switching requires re-learning weather intuition from scratch.

The Conversion Formula

Converting between scales is straightforward:

  • °C to °F: multiply by 9/5, then add 32 → (°C × 1.8) + 32
  • °F to °C: subtract 32, then multiply by 5/9 → (°F − 32) ÷ 1.8

A handy shortcut for weather: double the Celsius temperature and add 30 gives a rough Fahrenheit value. So 20°C ≈ 70°F (actual: 68°F) — good enough for casual conversation.

Which Scale Is Better?

For science, Celsius wins handily — its anchors in water's phase transitions make it universally meaningful. For everyday weather in the US context, Fahrenheit offers more granularity in the comfortable range (most people live between 0°F and 100°F most of the time, while the Celsius equivalent is −18°C to 38°C, a less intuitive spread).

Kelvin, used in science for thermodynamic calculations, simply adds 273.15 to Celsius, setting absolute zero (the coldest possible temperature, where molecular motion stops) at 0 K.

Will the US Ever Switch?

Most trade and technical sectors in the US already use metric and Celsius — medicine, science, the military, and manufacturing. The consumer holdout is cultural. Given that metrication attempts have stalled for 50 years and each generation learns Fahrenheit as a native, a near-term switch seems unlikely absent regulatory mandate. The rest of the world, meanwhile, finds the situation baffling and amusing in roughly equal measure.