Use a dash (not a hyphen) for overlapping, two-year spans.
Also use a dash for multiple-year spans.
Write months in full and write "to" rather than using a dash between dates.
Monday, August 14, 2017
December 4 to 6
When dates – including the month, day and year – appear in a sentence, put a comma after the year.
January 1, 2017, was the first day the agreement came into effect.
In 2020, new regulations took effect in Yukon which ended the practice of "falling back" an hour in November and "springing forward" an hour in March. Yukon now observes Pacific Daylight Saving Time year-round. It's called Yukon Standard Time.
Not: Yukon Time, Yukon time, UTC -7
But: Yukon Standard Time, UTC-7
Use "to" rather than a dash or hyphen between times.
Not: 10:00 a.m., 10:15 a.m., 10:00 a.m. – 11:00 a.m., 2pm to 3pm, 11.30am to 12.30pm
But: 10 a.m., 10:15 a.m., 10 a.m. to 11 a.m., 2 p.m. to 3 p.m., 11:30 a.m. to 12:30 p.m.