Information about rainfall and temperature averages can be extremely useful, however relying only on averages is somewhat conceptually flawed in the context of agriculture, because an average can tend to obscure any extreme measurements. This issue is pertinent, especially in regards to temperature, because the cold can kill plants. The danger to plants is compounded now by the cold weather extremes observed over the past two winters here in North America (My experience is with Canada). The 'arctic jet-stream', also known as the 'polar vortex' is not reflected in the average data presented on that site.
I get the sense that looking at data that is more granular would give us more useful information to work with. I found just that kind of data recently. The data displayed are: absolute min/man and average min/max. It is presented in a graphical format that is easy to interpret and the individual measurements can be seen by hovering the mouse over the graph. The link provided is for my geographic location specifically, but the location can be changed with the "Fast Forecast" text box on the left. Please make sure to select the "Climate" tab and scroll down about midway to see the graph I am talking about, it is titled Temperatures: Averages and Extremes and is under the YEARLY TRENDS: WEATHER AVERAGES & EXTREMES sub-heading.