After the summer months museum traffic gets slower, tourism trickles and museums get a break - usually (the world over) on MONDAYS. Though sometimes Tuesdays too....and some don't open till 10:00 (which for the young crowd is L-A-T-E LATE!
And to confuse you (or at least me) more, the ones that are closed on Monday are often open if it's a HOLIDAY Monday. Always check in advance.
The other international museum rule - Thursday nights are Free...at least if they're open! and the last hour of opening (often 4:00-5:00) is also often free.
So that you don't make the same mistakes I have and so that perhaps the hours will become ingrained in my brain by writing this, here are the WINTER HOURS of the key Ottawa family museums. If in doubt please check the official museum websites. Frankly that's always a good idea....
- Canada Agriculture Museum (aka the Farm) - actually open every day from 9-5 since the animals always need to be fed. Main exhibit buildings do eventually close for the winter though the barns always remain open (great for a winter walk with occasional mildly warm refuge out of the wind with the sheep or pigs or horses). The exception that proves the rule. They have fun special events for both Thanksgiving and Halloween (one or two chocolates to be found maybe??) http://www.agriculture.technomuses.ca/
- Canada Aviation and Space Museum - Open from Wednesday to Monday (yes they are open on Monday - thanks to Mary@parenthood for correcting me) from 10:00 - 5:00. (note that, 10:00, probably becuase this museum really is for the slightly older of the young crowd) http://www.aviation.technomuses.ca/
- Canada Science and Technology Museum (aka Science and Tech) open from Tuesday to Sunday from 9:00 - 5:00, closed Mondays, except holidays. Note that they have a great new little kids play area and the current exhibit "In Search of the Canadian Car" is excellent. Have always loved this museum. http://www.sciencetech.technomuses.ca/
- Canadian Museum of Civilization and the Childrens Museum: Tuesday through Friday 9:00 - 5:00 but Thursdays open till 8:00 pm (Free admission Thursday evenings); Saturday and Sunday 9:30 - 5:00. http://www.civilization.ca/
- Canadian Museum of Nature: Tuesday to Sunday from 9:00 - 5:00, Thursdays 9:00 - 8:00 (with Free admission on Thursday evenings) http://www.nature.ca/.