The Vegetation of Western Australia. 
XXXlll. 
RAINFALL FOR KATANNING, 1891-1941. 
(Average 1,873 points.-) 
Year. 
Annual 
Total. 
Departure 
from Mean. 
Year. 
Annual 
Total. 
Departure 
from Mean. 
1891 .... 
1,236 
points 
-- 637 
0/ 
/o 
34 
1917 .... 
2,566 
points 
+ 693 
9/ 
/o 
37 
1892 .... 
1,568 
— 
305 
16 
1918 .... 
2,316 
+ 
443 
24 
1893 .... 
1,621 
— 
252 
13 
1919 .... 
1,700 
— 
173 
9 
1894 .... 
1,293 
— 
580 
31 
1920 .... 
1,975 
102 
5 
1895 .... 
1921 .... 
2,080 
+ 
207 
11 
1896 .... 
1,440 
— 
443 
24 
1922 .... 
1,605 
• — 
268 
14 
1897 .... 
1,274 
- — ■ 
599 
32 
1923 .... 
2,394 
521 
28 
1898 .... 
1,770 
— . 
103 
6 
1924 .... 
1,715 
— . 
168 
9 
1899 .... 
1,784 
■ — 
89 
5 
1925 .... 
1,972 
99 
5 
1900 .... 
2,133 
260 
14 
1926 .... 
2,461 
588 
31 
1901 .... 
1,649 
— 
224 
12 
1927 .... 
1,776 
— 
97 
5 
1902 .... 
1,429 
— 
444 
24 
1928 .... 
1,862 
— 
n 
1 
1903 ... 
2,431 
538 
30 
1929 ... 
2,024 
+ 
151 
8 
1904 .... 
2,023 
150 
8 
1930 ... 
1,943 
+ 
70 
4 
1905 ... 
2,453 
580 
31 
1931 .... 
1,915 
+ 
42 
2 
1906 .... 
1,936 
63 
3 
1932 .... 
2,278 
+ 
405 
22 
1907 .... 
1,948 
75 
4 
1933 .... 
1,972 
99 
5 
1908 .. 
1,454 
— 
419 
23 
1934 .... 
2,068 
+ 
195 
10 
1909 .... 
2,066 
+ 
193 
10 
1935 .... 
1,700 
+ 
173 
9 
1910 .... 
2,013 
4- 
140 
7 
1936 .... 
1,525 
— 
348 
19 
1911 .... 
1,610 
— 
263 
14 
1937 .... 
2,215 
342 
19 
1912 ... 
1,583 
— 
290 
15 
1938 ... 
1,384 
— 
489 
26 
1913 ... 
2,468 
-f- 
595 
32 
1939 .... 
2,718 
00 
Or 
45 
1914 .... 
1,593 
— 
280 
15 
1940 .... 
1,072 
— 
801 
43 
1915 .... 
2,189 
316 
17 
1941 .... 
1,857 
— 
16 
1 
1916 ... 
1,588 
— 
285 
15 
Mean var.— 16 
•1 
2. TEMPERATURE. 
The annual mean temperatures show little correlation witli the vegetation 
in general, but are of importance in limiting the megathermic elements. Tlie 
mean isotherm of 80° F. for January and February — the driest months in tlie 
soutli — closely approximates to the southern boundary of the Mulga forma- 
tion, but this may be little more than a coincidence. What is of more im- 
portance is the temperatin-e range, especially the diurnal range. While tlie 
coastal temperatures remain fairly equable, high diurnal variations an? ex- 
})erienced in the interior, especially in the arid areas ; even in the soutli-west 
tliey r(‘main extreme at such stations as Bridgetown and Katanning. The 
\ariation between the monthly maxima and the montlily minima are pro- 
Ijortionately high, being 45° F. at Katanning, 53° at Kellerbcn-rin, and rising 
to ()0° at Muiidiwindi. I’liese temperature extremes, especially the diurnal 
extremes, are comparable in tlie cases of Wiluna and Mundiwindi, with those 
of the desert of the Punjab ! A study of the monthly isotherms shows an 
interesting correlation between the temperature and the vegetation, ami 
wlien applied to the months of maximum precipitation explains satisfactorily 
the extent of the grassland and woodland formations. 
