In the present tense, it is usual to use the phrase estamos a (literally, "we are") to discuss the temperature being experienced by the speaker and the persons around him or her. Está a (literally, "it is") is used to discuss the temperature of other places. See the following examples:
- Estamos a 30 grados. (It's 30 degrees.)
- Si la temperatura está a 2 grados o más, los niños juegan afuera excepto si llueve o nieve. (If the temperature is 2 degrees or higher, the children play outside unless it's raining or snowing.)
- Estamos a 10 bajo cero. (It's 10 below zero.)
- Hace una semana estaban a 30 grados, pero ahora estamos a 10. (A week ago it was 30 degrees, but now it's 10.)
- ¡Cuántas veces el aire está a 15 grados mientras que el agua está a 17! ("How often the air is 15 degrees while the water is 17!")
- Oscila entre 8 y 20 grados centígrados. (Temperatures vary between 8 and 20 degrees centigrade.)
- Colocar en horno a 200 grados durante 15 minutos. (Set in a 200-degree oven for 15 minutes.)
- El agua del mar Mediterráneo alcanza los 32 grados de temperatura. (The water of the Mediterranean Sea reaches a temperature of 32 degrees.)
- Las bacterias se reproducen a una temperatura entre 20 y 30 grados. (The bacteria reproduce at a temperature of 20 to 30 degrees.)
- C = 5(F-32)/9
- F = 9C/5 + 32
Of course, mathematical precision isn't always necessary. Here's how I often think of temperatures in Celsius:
- -20 degrees C or below (-4 degrees F or below): frigid (muy frío)
- -20 to 0 degrees C (-4 to 32 degrees F): cold (frío)
- 0 to 10 degrees C (32 to 50 degrees F): cool (fresco)
- 10 to 20 degrees C (50 to 68 degrees F): mild (templado)
- 20 to 30 degrees C (68 to 86 degrees F): warm (caliente)
- 30 to 40 degrees C (86 to 104 degrees F): hot (muy caliente)
- 40 degrees C and above (104 degrees F and above): unbearably hot (insoportablemente caliente)

