Weather in Whyalla in December

Prime time. If you get to pick your dates, December is the one. Highs average 29.5 °C, lows 17.9 °C, and rain falls on 3 days — nothing in the month is working against you.

December ranks 7 of 12 in Whyalla: past the worst of the year but short of October, which is the month to book if the dates are open.

Rain falls on only 3 days, so an itinerary with no wet-weather fallback is a reasonable risk. Pack for 29.5 °C days and 17.9 °C nights; the spread matters more here than any single number.

What the averages hide

Averages flatten a month, and this one hides a few things: 5 days clear 35 °C, so a serious heatwave is normal rather than notable. Across the twenty years measured, the hottest December day reached 45 °C and the coldest night fell to 12.1 °C, and the wettest single day dropped 38 mm — roughly 190% of the month's rain in one day.

This is the volatile part. December rainfall has ranged from 0 mm to 65 mm across the twenty years measured — a 65 mm spread around an average of 20 mm. The average is real but almost no individual December looks like it, so treat the figure as the middle of a wide range rather than a forecast.

Wind is light at 15.9 km/h, so the temperature on the page is close to the temperature on your skin, and humidity is unremarkable at 50%.

How December sits in the year

The month is on the way up: 2 °C warmer than November, and January adds another 2.2 °C. Late in the month feels noticeably different from the start of it, which is worth knowing if the trip is short.

Daylight in December

December is at or near the longest days of Whyalla's year: 14.3 hours of daylight, holding steady all month. Evenings are the real gain — dinner outdoors still happens in full light.

An inland climate

Despite being inland, the year stays fairly even: 23.7 °C between the year's warmest afternoons and coldest nights.

How busy it gets

Busy. Popular without being frantic; book the things you care about, improvise the rest.

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

December in Whyalla versus nearby

If Whyalla is one option among several, the nearby comparison is worth making. Gawler is close enough to be a coin toss — within a degree on temperature, 1 day more rain. Adelaide is close enough to be a coin toss — within a degree on temperature, 1 day more rain.

So: December works, with October the better month by 11 points if the dates can move. If they cannot, nothing here should stop you booking.

Every month in Whyalla

See all twelve months in Whyalla, or where else to go in December.