Why my calendar field is not showing is English?

Hello..

I`m from Brazil and the month of my callendar don`t show in English. Just portuguese. Can you say me why?

Look.. http://fabriciowillian.com.br/projetos/travel/make-a-plan/

thanks!

I checked your form and I couldn't replicate this error, for me the Calendar is showing in English:

Please let us know if the issue persists or if you had something else in mind.

Thank you!