Weather in Greymouth in May

A hard month. May asks something of you. Go in knowing what. You should expect rain on 17 days of the month, which is more days wet than dry.

May ranks 8 of 12 in Greymouth: past the worst of the year but short of February, which is the month to book if the dates are open.

This is wet-season rain: 17 wet days and 6 genuinely heavy ones, which in this climate means concentrated downpours rather than all-day grey. The pattern is usually a clear morning and a loud afternoon, so front-load the day and stop fighting the 3pm hour. Layers, and a genuinely waterproof outer — at 14 °C the difference between a good day and a miserable one is entirely down to what you are wearing.

What the averages hide

Averages flatten a month, and this one hides a few things: the day barely swings — 4.5 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest May day reached 19.3 °C and the coldest night fell to 2.2 °C, and the wettest single day dropped 53 mm — roughly 29% of the month's rain in one day.

May is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest May on record still delivered 369 mm against 64 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 180 mm average is a reasonable planning figure, not a promise.

Wind is light at 4.9 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 88%, which at 14 °C means damp rather than muggy — the kind of cold that gets into a coat and stays there.

How May sits in the year

The month is on the way down: 2.2 °C cooler than April, with June dropping another 2 °C. The first week and the last are not the same trip.

Daylight in May

9.8 hours of daylight, losing 1 hours across the month. That is between Greymouth's extremes of 15.3 and 9.1 hours, so days are long enough not to constrain the plan.

Sea temperature

The sea sits at about 16.1 °C in May — cold — a quick dip rather than a swim, and a wetsuit if you are in for longer. The sea peaks at 18.5 °C in February and bottoms out at 13.3 °C — water lags the air by a month or two, which is why the best swimming often comes after the best weather.

How busy it gets

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

May in Greymouth versus nearby

If Greymouth is one option among several, the nearby comparison is worth making. Waikowhai is close enough to be a coin toss — within a degree on temperature, 1 day more rain. Christchurch is a better bet in May — within a degree on temperature, 3 days less rain.

So: May is a compromise. February is 26 points better and is what Greymouth is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Greymouth

See all twelve months in Greymouth, or where else to go in May.