A temperature of 1 degree Celsius (1°C) places the air right on the edge of winter’s most impactful weather conditions. The Celsius scale, which is the standard for most of the world, defines its zero point based on the physical properties of water. This makes 1°C a highly relevant marker for atmospheric science and for anyone planning to step outside. Understanding how cold 1°C feels requires considering its proximity to a major scientific threshold.
The Proximity to Freezing
The Celsius scale establishes the freezing point of pure water at standard atmospheric pressure as 0°C. Consequently, 1°C is just one degree above this phase change, meaning water remains in its liquid state. This slight margin means that precipitation falling from the sky will typically be rain, not snow, when the air temperature is measured at this level.
However, the temperature of the air and the temperature of surfaces are not always identical. While the air may be 1°C, surfaces like bridges, roads, or ground can cool more rapidly through radiation. These microclimates can drop to 0°C or below, allowing residual moisture or standing water to freeze and create frost or slick conditions. A shallow layer of sub-freezing air near the surface, even with a 1°C reading aloft, can also lead to complex precipitation types like wet snow or sleet.
Understanding the Temperature in Other Scales
For those more familiar with other systems, 1°C translates to 33.8°F on the Fahrenheit scale. This reinforces the idea of being just above freezing, as 32°F is the point where water turns to ice on that scale.
The Kelvin scale, the International System of Units (SI) reference for thermodynamic temperature, provides a scientific perspective. Kelvin uses absolute zero, the point where all thermal motion theoretically ceases, as its starting point of 0 Kelvin (K). To convert Celsius to Kelvin, one simply adds 273.15 to the Celsius temperature, making 1°C equivalent to 274.15 K. The Kelvin scale uses increments of the same magnitude as the Celsius scale.
What 1°C Feels Like Outdoors
Outdoors, 1°C is distinctly cold and requires thermal protection for comfort and safety. The body attempts to maintain a core temperature of approximately 37°C, meaning the air temperature causes a rapid loss of heat. Heavy layers of clothing, including insulated jackets, hats, and gloves, are necessary to create an insulating boundary layer of warm air around the skin.
The perception of cold is often increased by the presence of wind, a phenomenon known as wind chill. Wind accelerates the rate of heat transfer away from the body, making exposed skin feel much colder than the measured air temperature. For example, a 1°C temperature with a moderate wind of 16 kilometers per hour can feel closer to a sub-zero temperature.
High humidity often associated with this temperature also contributes to the chilling sensation. Precipitation at 1°C is most likely rain, but it may be a cold, damp mist or a mix of rain and wet snow. This dampness enhances the conductive cooling effect. The combination of cold air, wind, and dampness demands caution and warm, water-resistant clothing.