That’s entirely a matter of habit. There is nothing special about 0°F or 100°F, you’ve been lied to.

We don’t think -18°C to 38°C, we think -50°C to +50°C, with 0°C differentiating between snow/ice, “wintery” weather, and rain/mud, “non-wintery” one. That’s how we know whether to take umbrella (no point if it snows, hat is your best friend), what kind of shoes are the best fit - cold-resistant or highly waterproof - or which kind of jacket is gonna fit the situation.

When it’s not winter, normal range is 0-40°C, with 20°C designating comfort temperature.