Programmatically add a translation of month
Use string overrides directly in either your settings.php file or through the string overrides module. See this note for specifics, this also lets you migrate this string overrides snippet from site to site either through simple cut and paste or through the string overrides migrate extension. This also deals with strings not yet known to the locale UI through t().

Example: 

 $conf['locale_custom_strings_en'][''] = array(
   'January'      =&gt; 'New string 1',
   'February'      =&gt; 'New string 2',
 );