FREAK HEAT WAVE. RECORD NIGHT TEMPERATURE. 09 April 1938. Not for many years had there been such remarkable weather in Perth as the excessive heat of Thursday night. No March or April heat waves found since 1950.

FREAK HEAT WAVE. (1938, April 9). The West Australian (Perth, WA : 1879 – 1954), p. 19. Retrieved April 15, 2021, from https://trove.nla.gov.au/newspaper/article/41215074?searchTerm=april%20heat%20wave&searchLimits=#

Minimum Just Before Dawn.
Not for many years had there been such remarkable weather in Perth as the excessive heat of Thursday night.
A maximum temperature of 93.9deg. in April is in itself abnormal, but that the peak should have been reached at nearly 10 o’clock at night was unprecedented.
Although the Weather Bureau does not keep records of the time at which the maximum temperature occurs each day, officials could not recall a previous case of its occurring so late. Nor could they discover, even after a reference to the record heat wave figures of February,
1933, a night on which the mercury stood at more than 90deg. at 10 o’clock.
The temperature remained in the eighties until almost daybreak yesterday, the minimum, 70deg, being recorded at 6.15 am.
There was little fluctuation yesterday, the maximum being 78deg. at 3.10 p.m. Another unusual feature was that, apart from the brief thunder squall in Perth on Thursday night, the extreme heat was followed by neither severe storms nor heavy rain.
With weather conditions topsy-turvy, people in the suburbs on Thursday night were at a loss to find means of keeping cool The orthodox procedure on a normal hot night would be to throw
doors and windows wide to catch a breath of cool air, but those who were tempted to do this on Thursday night were met with a wind from the north like a blast from a furnace.
Houses were shut up again hastily and people went to bed with doors and windows closed to
keep out the heat. They told one another that there was a big storm working up, that it would be blowing a hurricane by morning, and that the warm night no doubt presaged torrential rain. Yet morning broke with conditions just as placid as they had been on the previous day.
Comparison with Other Years.
The hottest night ever experienced in Perth was the night of February 7, 1933, when the lowest point to which the temperature fell was 87.7 degrees.
Yet even that night was probably less severe than Thursday night when the temperature was between 80deg. and 93.9deg. from 9 p.m.to 4 am. The minimum of 70deg. was nearly 13deg. above the average April minimum, and has been exceeded only twice on April 15, 1937 (72.8deg.) and April 1, 1927 (74deg).
The only 10 p.m. readings approaching that of Thursday night which could be found in Weather Bureau records were 88deg. on February 3, 1933. 88.7deg. on February 7, 1933, 79.8deg. on February 8. 1933, and 88.7deg. on February 25, 1934.
The average maximum temperature for April is 76.3deg. and the average minimum 57.3deg. The highest reading ever recorded in April was 99.7deg. on April 9, 1910, and Thursday’s maximum has been exceeded in April only four times during the past 16 years-97deg. on April 1 last year; 95.9deg. on April 12 and 16, 1928, and 95deg. on April 12, 1922.
How Thursday night was hotter than the hours of daylight which preceded and followed it is shown in the following table, which give the hourly temperature and humidity readings from 9 a.m. on Thursday to 5 pm. yesterday:
Temperature. Humidity.
am. Degrees. Per Cent.
9 74.0 67
10 76.5 61
11 78.0 60
Noon 82.5 58
pm.
1 87.6 47
1.20 88.1 46
3 87.5 46
4 87.2 42
5 87.0 42
6 80.8 53
7 79.7 60
8 78.4 62
9 85.8 49
9.50 (max) 93.9
10 91.8 25
11 88.3 25
Midnight 89.7 23
a.m.
2 87.7 24
3 82.9 27
4 81.7 28
8.7
5 73.4 50
6 70.5. 81
6.15 (min.) 70.0
7 70.6 85
8 71.0 86
9 72.2 80
10 72.9 78
11 75.6 70
Noon 75.0 71
p.m.
1 75.5 70
2 75.0 70
3 72 65
4 75.0 70
5 75.2 71
Turbulent Atmosphere
Questioned yesterday regarding the reason for the excessive night heat, the Acting-Divisional Meteorologist (Mr. W.L. Nelson) said that it was due to turbulence of the atmosphere, which was responsible for all sorts of erratic conditions.
The conditions on Thursday night were caused by a southward extension of a tropical low pressure, which brought about a north-easterly wind circulation and a consequent rise in temperatures over the inland areas, and also by a south-westerly wind circulation over the coastal areas.
The combination of these two factors resulted in a pressure distribution conducive to the development of thunderstorms. During the night there were several sharp fluctuations in
humidity due to sudden changes in the direction of the wind.
There was a further slight fall In barometric pressure over the sub-tropics yesterday afternoon, but otherwise the pressure distribution was similar to that of the morning, said Mr. Nelson. Reports from the inland areas showed high temperatures throughout the East Gascoyne, northern goldfields and eastern wheatbelt, stations in those areas reporting over 100deg, with a maximum of 103deg. at Southern Cross and Yalgoo.
Temperatures were moderate in the west and south-west coastal areas and the extreme south, but in the tropics most stations reported over 100deg.,
Marble Bar being the highest with 106deg. It was expected that today conditions would be
still sultry over most of the sub-tropics. Moderate temperatures with south-west to south-east winds were to be expected in the western and southern districts, and continued heat inland with chiefly north-easterly winds.