Average Date When Mean Daily Minimum Temperature Crosses 32 Degrees F.—Concluded ; Period McBride sa se) ee eae May. 8° =: Oct oan aap 156 days Dome (reek. 2et peer May 218 Octa 4a a5 -amees 136 days Barkerville. 00) - May 15 — Sept. 29.0001! 137 days Fort Norman eee eee May 24 - Sept. 18......... 117 days Fort Simpson............. May 43 ~ Sept: 24. 5 ye 134 days Fort Good Hope........___ May 26 —Sept. 12......,_. 109 days Fort Resolution......... =. May 18 - Sept. 30.....0. | 135 days Hay Rivers. 5st oe (sto May 23 - Sept. 27......._. 127 days Fort Smithe ayo pees May 13 - Sept. 21.......- 131 days ANiclasyi kes, che og Witabe ane June 6 — Sept. 14...... 9 100 days Fort McPherson..........- May 30 Sept. 14......__. 107 days Great Slave Lake— Hondiduilace sang) see May 3-26. = Octi=8 2 eee eee 129 days Fort Chipewyan......... May 13 - Sept. 30.......__ 140 days Peace—Athabaska— heMicMurrays ss pees oe Acyl Sep =o ee 137 days Fort Vermilion........_. May 13 -Sept. 18......... 128 days iphuPrairien= amma! Maya 2) Sept o7 saan a 148 days Beaverlodge............. JN ep (Oe Wy 155 days Ores bse) Oh sess ee mens EN es PI) Ol 7 161 days ¥ Hudson Hope........... May 13 = Sept. 28......... 138 days Calor yea este cha IMlesr Dre (Ola 154 days The date upon which and after which the mean daily lowest temperature is above the freezing-point is the best measure of the growing-season. Growth, then, continues both night and day. Erratic frosts may occur after this date and temporarily check the growth of hardy plants, or May even destroy plants of tender vigour and necessitate ‘replanting. Yet the time elapsed between the first and last dates of average daily minimum of 32 degrees F. is a good basis of comparison of at least the maximum cultural | possibilities of districts. There is, then, 136 days, by this indicator for St. Walburg, Sask., near the northern margin of wheat-cultivation on the prairies, and find that the Yukon valleys fall 10 days short. At Watson Lake and Fort Nelson airports the short period of record looks better, especially at Fort Nelson. At Babine Lake and Fort St. James on Stuart Lake, the period is shortened 5 days to 15 days. Vanderhoof averages nearly the same, but Wistaria on Ootsa Lake is identical with St. Walburg. Dates in Year—Days............... Jan. 1....Year—Day 1 New Hazelton, Telkwa, Terrace, and Prince George compare well with Calgary’s 154 days. Dome Creek, on the north- flowing Fraser, and Barkerville on the interior plateau are the same as St. Walburg, whereas McBride has as long a season as Calgary. This may be quite local and affected by the lake nearby and the local fog-blanket on frosty nights, such as often forms over Lake Okanagan on winter nights. The Mackenzie Valley looks poor in comparison, with 100 | to 110 days from the delta lands to the Arctic Circle and 127 to 135 elsewhere along the river and the lakes. The figure of 134 days at Fort Simpson seems to be high compared with 131 days at Fort Smith. Yet the difference has per- / sisted over many years. Possibly the waters of the Liard’ discharging from British Columbia at Fort Simpson may have a purely local effect. There is a very large difference’ between Fond du Lac and Chipewyan at opposite ends of Lake Athabaska, but Chipewyan has an above-freezing period 4 days longer than St. Walburg. Fort Vermilion experimental station is short by one week. It is recom: mended that the experience of this farm over a long period be checked against experience in the St. Walburg area to determine the real significance, if any, of this deficit of one week. Since Beaverlodge farm has as good a record as Calgary, and Fort St. John (Baldonnel station) averages better and High Prairie averages only a week less than Calgary, it can be seen that the successful growing of wheat in the Peace River area is at least approximately related to the length of the above-freezing period. Hudson Hope has approximately the same winter temperatures as Baldonnel, but from April to the middle of October Hudson Hope has minimum temperatures three or four degrees lower. Pouce Coupe is also somewhat cooler, which indicates a less favourable condition at least locally in the British Columbia portion of the Peace River Valley. Consideration may now be given the records that have been accumulated on the incidence of late and early frosts. These give us some idea of the unforeseeable hazards that may afflict the agriculturist in some seasons. JEG he Year—Day 32 Dec. 31... . .Year—Day 365 Last Frost of Spring First Frost of Autumn Average : Frost-Free Station Earliest Latest Average | Earliest Latest Average Period Days Days Days Days Days Days Days Barkervilles sarretud nc th sarin asics sce Weleaee ee oee 143 197 174 197 262 228 54 Wome Greek t.