I am using date_popup in a form and I want the months and weekdays appear in my custom language; how can I achieve this?

$form['custom_date'] = array( '#title' => t('date'), '#required' => TRUE, '#weight' => -10, '#type' => 'date_popup', '#date_format' => 'd/m/Y', '#default_value' => date('YYYY-MM-DD HH:MM:SS',($node->data_assentament>0 ? $node->custom_date : time())), '#size' => 12, );

thanks