Archive pages with full month names?
Twig’s date filter is aware of the current Craft locale, so you should be able to create a DateTime after composing a string that the filter accepts (see PHP strtotime function docs, which the filter uses behind the scenes).

{% set day = 1 %}
{% set month = 'juni' %}
{% set year = 2016 %}

{% set dateString = [day, month, year]|join(' ') %}
{% set date = dateString|date %}

{{ date }}