March — days, dates and countdowns

How to use March

Use the grid to place the equinox, the clock change and any quarter-end deadlines against real weekdays. March is a month where two dates move: the equinox falls on the 19th, 20th or 21st depending on the year, and the daylight saving switch depends on your country's rule, not on a fixed number.

If you are scheduling anything across countries in March, check both ends. There are weeks in this month where the usual gap between two cities is an hour different from normal, because one has changed its clocks and the other has not yet.

Three things that move in March

The vernal equinox — day and night close to equal length, marking astronomical spring in the north and autumn in the south. It falls at a specific instant, so its calendar date depends on your time zone.

Daylight saving — clocks go forward in Europe and North America, but on different dates. That mismatch lasts weeks, not days. Financial year ends — several countries close their fiscal year in March, which makes the final week unusually busy for anything involving accounts.

Nothing exposes a badly written meeting invite like the fortnight when half the world has changed its clocks and the other half hasn't.

Losing an hour, and what it costs

Where daylight saving begins, one night is 23 hours long. The clock jumps, usually from 2am to 3am, and the hour between simply does not exist locally. That has practical consequences: an alarm set inside the missing hour may not fire, a shift that spans it is an hour shorter, and anything scheduled to run at that local time needs a rule for what to do when the time is not real.

Date arithmetic is mostly unaffected — the day count stays the same — but duration arithmetic is not. A "24 hours from now" calculation across that night lands an hour off the same clock time, and that is correct behaviour, not a bug.

Getting through the month cleanly

Confirm the daylight saving date for every country in a recurring meeting, not just your own. Move any process that runs in the small hours away from the switch window for that one night. Treat quarter-end and financial year-end as separate deadlines even when they look adjacent.

For outdoor plans, use the equinox as a rough marker of usable daylight rather than of weather — the two are not the same thing.

The name, and the missing two months

March is named for Mars and was once the first month of the Roman year, which is the cleanest explanation for the calendar's oddest feature: September, October, November and December mean seventh, eighth, ninth and tenth. Count from March and the names come out exactly right. January and February were added at the front later, pushing every numbered name two places out of position, and nobody has ever bothered to fix it.

It is a good reminder that the calendar is not a designed system but an inherited one, patched repeatedly and never rebuilt.