Estimating the metric weather

Americans really have no need for metrification, since we use the same system everywhere. Most of us have to travel across an ocean, or at least to another country, before we have use for the metric system in everyday life, outside of specific contexts. And so I never really learned to make small talk about the weather in the metric system, even when I lived in a metric country for a year and a half.

But it's probably not all that hard to convert mentally: 5°C is 9°F. So a Celsius temperature in the low teens corresponds to a Fahrenheit temperature in the 50s, while a Celsius temperature in the high teens corresponds to a Fahrenheit temperature in the 60s.

Celsius	Fahrenheit
0-5°C	32-41°F
5-10°C	41-50°F
10-15°C	50-59°F
15-20°C	59-68°F
20-25°C	68-77°F
25-30°C	77-86°F
30-35°C	86-95°F
35-40°C	95-104°F
40-45°C	104-113°F
45-50°C	113-122°F

More broadly, around here in Kentucky, temperatures in winter are usually in the 00s, spring in the 10s, summer in the 30s, and fall in the 20s. In Louisville it very rarely breaks 40°C, but when I was a kid in Oklahoma it sometimes got over 45°C, I remember seeing a record high of 49°C (120°F).

OTOH, the metric system is very useful in cooking, since a cup is 240 mL, a tablespoon 15 mL, and a teaspoon 5 mL.

EDIT
It occurs to me the reason I never learned to estimate the temperature in Celsius, while living in a metric country, was that I spent much time precisely calculating the Celsius-to-Fahrenheit conversion. A simpler conversion, like "double the Celsius temperature and add 30" would have been better: quicker and easier and nearly as accurate.

Also, strikethough an egregious error :)