It is standard for countries to have a provision in their IP legislation whereby filing deadlines that fall due during a public holiday (or over a weekend) instead fall due on the next working day. While the next working day becomes the official filing date, it is still deemed to comply with the filing deadline.
Article 4C(3) of the Paris Convention, to which the vast majority of countries with IP legislation belong, also has such a provision for convention filings:
(1) The periods of priority referred to above shall be twelve months for patents and utility models, and six months for industrial designs and trademarks.
(2) These periods shall start from the date of filing of the first application; the day of filing shall not be included in the period.
(3) If the last day of the period is an official holiday, or a day when the Office is not open for the filing of applications in the country where protection is claimed, the period shall be extended until the first following working day.
Particularly for new applications, the details of an invention or design should not be publically disclosed until after the official filing date so as not to potentially compromise novelty.
The website http://www.timeanddate.com/holidays/ usefully gives holiday information for most countries as well as a calendar of upcoming holidays.