Since the year's almost up I had a look at the daily data for Halifax Dockyard. I'll clean it up a bit once December 31 is recorded and I get some time but here's what the numbers are so far.
Average annual high: 11.7
Average annual low: 4.0
Annual average: 7.9
Warmest daily high: 34.4
Coldest daily high: -7.1
Warmest daily low: 18.7
Coldest daily low: -15.1
A preliminary chart:
It's interesting to see how the daily variability drops so much when going into springtime, while winter is all over the place. It was a below average winter for nightly lows but not highs. I suspect that 34.4 day (July 5) is a big outlier too. There are probably plenty of years when this station doesn't hit 30.