EDIT: Weather Bureau says predictions for north Australian rain under climate change have gone both ways.
EDIT: Cyclone Lili formed late off Dili after this post, and was still going on May 10.
EDIT: Cyclone Ann formed far from Queensland coast in May and was still going on May 14.
Australian Weather Bureau says one May cyclone in the region is not unusual, but two is rare, according to records from 1970s.
Bureau says cyclone predictions under climate change may include fewer, but more intense storms.
Note that cyclones can form in the southern hemisphere as late as July, usually in the Coral Sea.
Separately, a quote from the same Australian Bureau of Meteorology Tropical Note at the time of this original post ...
Unprecedented tropical cyclone activity in southwest Indian Ocean
Less than a month since tropical cyclone Idai made landfall on the central Mozambique coast as one of the most destructive tropical cyclones to affect the southern hemisphere, in terms of impacts, another intense tropical cyclone, Kenneth, made a direct hit on the southern African country. Kenneth was the first tropical cyclone on record to make landfall on the northern coast of Mozambique and was also the most intense tropical cyclone to make landfall on Mozambique in recorded history. Kenneth was the equivalent of a category 4 tropical cyclone on the Australian scale, with sustained winds to 200 km/h, when it made landfall on 25 April. Many fatalities have been reported, along with widespread damage to infrastructure, vegetation and crops. Kenneth generated very heavy rainfall, in excess of 500 mm in some locations, and caused significant, widespread flooding.
Another weaker system, ex-tropical cyclone Lorna, which peaked at an intensity comparable to an Australian category 3 system, dissipated over the central southern Indian Ocean in the past 24 hours, just west of the Australian tropical cyclone region. This system remained over open water throughout its entire life cycle.
With the addition of Lorna, the 2018-19 cyclone season for the southwest Indian Ocean has seen a total of 16 storms, the highest number on record (previous record was 15 storms in 1993-94).