Is the word tempestades the same in Brazilian and European Portuguese?

Yes

The word "tempestades" is identical in meaning, spelling, and grammar in both Brazilian and Continental Portuguese. The only difference lies in pronunciation.

In Brazilian Portuguese, the vowels tend to be more open, and the unstressed "e" in the middle of the word is usually clearly articulated. In Continental Portuguese, vowels are much more "reduced" or closed; the unstressed "e" might sound like a very short, nearly silent "schwa" sound, and the rhythm of the word is more staccato.

Brazilian Portuguese Examples

1. As tempestades estão chegando com muita força. (The storms are arriving with a lot of force.)
2. Eu não gosto de tempestades durante a noite. (I don't like storms during the night.)
3. A gente passou por muitas tempestades este ano. (We went through many storms this year.)
4. Tem previsão de tempestades para o final de semana. (There is a forecast for storms for the weekend.)
5. As tempestades de vento derrubaram a fiação. (The windstorms knocked down the wiring.)

Portuguese (Continental) Examples

1. As tempestades estão a chegar com muita força. (The storms are arriving with a lot of force.)
2. Não gosto de tempestades durante a noite. (I don't like storms during the night.)
3. Nós passámos por muitas tempestades este ano. (We went through many storms this year.)
4. Há previsão de tempestades para o fim de semana. (There is a forecast for storms for the weekend.)
5. As tempestades de vento deitaram a fiação. (The windstorms knocked down the wiring.)