15 degrees Celsius = 59°F (exact). Rounded: 59°F. In Kelvin: 288.15 K. In Rankine: 518.67°R.
Cool to mild — typical spring/autumn weather in temperate climates.
For context: 0°C = 32°F (freezing), 20°C = 68°F (room temp), 37°C = 98.6°F (body temp), 100°C = 212°F (boiling). The Celsius scale places 0° and 100° at the freezing and boiling points of water at sea level.
All temperature units: 59°F · 288.15 K (Kelvin) · 518.67°R (Rankine). Kelvin starts at absolute zero (−273.15°C). Rankine is used in some US engineering applications.
Formula: °F = (°C × 9/5) + 32. For 15°C: (15 × 1.8) + 32 = 27 + 32 = 59°F. Reverse: °C = (°F − 32) × 5/9 = (59 − 32) × 0.5556 = 15°C.
15°C = 59°F (exact: 59°F). Formula: (15 × 9/5) + 32 = 59°F.
Multiply by 1.8 then add 32: 15 × 1.8 = 27, + 32 = 59°F. Quick estimate: double the Celsius value and add 30 → 60°F (approximate).
Add 273.15: 15 + 273.15 = 288.15 K. Kelvin is used in science — 0 K is absolute zero (the coldest possible temperature).
Cool to mild — typical spring/autumn weather in temperate climates. In Fahrenheit: 59°F is cool.