Fever degree

[lethargic_man]

I've been housebound with a temperature of up to 39¼°C (102½°F) since Wednesday evening. My mother said, "Oh, well we know you always run high fevers," but TBH I have no idea what temperatures are common for other people when they fall ill. So, what temperature do you go up to when you're feverish with a bad cold or flu?

Also: who still thinks of fevers in Fahrenheit and who in Celsius?