Is 30 Degrees Celsius Hot Or Cold?

Here are some translations to degrees Fahrenheit.
20 ºC = 68 ºF
25 ºC = 77 ºF
30 ºC = 86 ºF    (some would consider this warm enough to turn on the air conditioner)
35 ºC = 95 ºF
37 ºC = 98.6 ºF ("normal" human body temperature)

30 ºC is too cold to bake a pie, too hot to freeze ice. For a human, it is possibly uncomfortably warm, depending on exercise and humidity. As a daytime high temperature in the desert southwest (US), it might be considered cool.