It's very cold today, the weather outside is 12 degrees Celsius. It's still autumn and I am worried about the winter, it will probably be more intense then last year.

It's getting colder today, 12 degrees. It's still only autumn, so I'm worried that the winter will be harder than last year. Notes: - 'It's getting' is better than 'it's', it implies that the weather is changing - i.e. colder today than yesterday, probably colder again tomorrow. - Nobody outside the US uses units other than Celsius, so it is uncommon now to bother specifying them. - There is no need to state explicitly that you are referring to an outdoor temperature: weather is always outdoors. - I think you are taking the cold autumn weather as a sign of a cold winter coming, the logic is made clearer here. - We would usually describe an intense winter as cold or hard.

Camila, If you post next time under "Notebooks," it will be easier for people to show corrections they've made to the text.

good answer by Michael but he has made a "typo" it should be "than" not "then'" than is a comparison, Then is roughly same as "next".