Ask A Farmwest Climate Question

Question:  I need data on first and last frost free days for various locations in our area (Williams Lake).  Your degree days data is a good start to other info I need.  Any other suggestions?

Answer:  You need to obtain long term weather data for these locations and decide what temperature you consider to be critical for frost (depends on the crop since some crops tolerate temperatures below zero, and also noting that spring and fall critical temperatures are often different).  You will also need to decide what type of calcuation you will want - mean or probabilistic.

Question:  How can I obtain Degree Day Values based on 10 deg C for my Grape Vines? What is the relevance of publishing GDDs based on 0 deg C ie what commercial crops grow at these temps?

Answer:  Different crops have different baselines. We have now re-developed the calculator to allow a user to set their own baseline temperature.  You can select -5C to +10C.

Question:  I am trying to figure out the average annual evapotranspiration in the Salmon Arm area using your evapotranspiration calculator. Is it possible to access the data set for evapotranspiration to figure out what the typical monthly evapotranspiration is in the Salmon Arm area ?

Answer:  For design purposes we use an ET depending on the water storage capacity of the soil.  This is a daily Peak ET rate.

Peak Evapotranspiration Rates for Various B.C. Locations

The annual crop water requirement is listed below. You need to divide by the efficiency of the irrigation system for the gross water required.

Ie. If using hand line divide by 0.75. 16in / 0.75 = 21.3 in of annual requirement.

Estimated Annual Crop Water Requirements for Various B.C. Locations

The data on Farmwest will only be for single year. The above numbers are base on 30 years of data.  They come from the BC Irrigation Management guide.

Farmwest is using May 1 - Sept 30 Moisture deficit (MD) for a grass crop

2007   MD 543mm   21.37 in
2008   MD 510mm   20.0 in
2009   MD 568mm   22.4 in

You can set the date for each month too.  For example, 2008 ... 

May   MD 96 mm
June  MD 133 mm
July   MD 128 mm
Aug   MD 72 mm
Sept  MD 81 mm