I think it closes at least once a day during winter, somewhere around 5:00 pm, but it usually re-opens the next morning. Sorry, couldn't resist.
Historical refurbishments show it was closed for about two weeks in late January and early February during 2012, 2013 and 2015. It was not closed for that window during 2014 but was, instead, closed for about 2 weeks during December of 2013, so they probably moved it up by about a month. So, yes, it does seem a trend to be closed from mid January to early February.