Weather

Long, dry summer living up to its name in Perth

Craig McIntosh, 4 February 2018

Aside from two rain-bearing systems this summer, Perth is staying true to its reputation as the Australian city with the most sunshine and least summer rain.

Since the start of summer, there have been two periods of intense rainfall in Perth. The first being a strong cold front in mid-December, and the second being the leftovers of Ex-Tropical Cyclone Joyce which brought down loads of moisture from the north. Combined, these two events accumulated almost 140mm of rain. All the other precipitation recorded since the start of December adds up to a measly 7.6mm.

Typically at this time of year, Perth is relatively dry as the mid-latitude high pressure belt migrates south over the continent, pushing the westerly wind belt closer to Antarctica and the cold fronts that form within it. The result is dry winds from the land being blown over Perth, usually too dry for any significant cloud formation, so the sun shines more than not. The average time the sun shines in Perth throughout summer is around 11.5 hours per day, not leaving much time for rainfall. Upper soil moisture around Perth is almost non-existent at the moment.

Despite the lack of rain days, there is some good news. Perth Dam is currently storing over 42% of its capacity, up about 11% from this time last year. Root zone soil moisture is also quite high, benefiting from the downpours associated with Ex-Tropical Cyclone Joyce.

There is a hint of a few very light showers possible late Monday or early Tuesday as a cold front just reaches north to clip Perth. However, the forecast for the new week is for mostly sunny skies with temperatures reaching the high twenties and low thirties each day. The dry Perth summer is set to continue for a while yet.


- Weatherzone

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