Marc Hirrel, Docent

2016 marks a new beginning at SFNC with the installation of a weather station in one of the milkweed plots east of the cabin. This site was chosen over the cabin because the station will monitor soil temperature at a six inch depth. Data collected at this site will help to correlate spring green-up and flowering of our milkweeds with both soil and air temperature along with rainfall.

We could just rely on the internet weather sites such as Weather Underground maintained by the Weather Channel ( Such sites compile data from hundreds of locations across the country and the world. For us at South Fork, we could use data from nearby reporting stations in Clinton and Heber Springs. Even though Clinton is only 5 miles from us, our weather can be quite different. Greers Ferry Lake influences the weather on our peninsula, especially rainfall. This past year, rainfall monitored at the milkweed plots showed an inch more rain for the eastern plots compared to the western plot. Thus, the importance of on-site monitoring.

The instrumentation consists of two data acquisition units. One tracks daily maximum and minimum soil and air temperature for six days. The other is a tipping bucket rain gauge that stores rainfall for nine days. The units are housed in a weather proof plastic box that provides easy access to each unit. Both instruments were inexpensive with a combined cost of under $100.

Below is a summary of weather for two reporting periods in 2016. As one would expect the soil temperatures never got below 32F and variation was less than 10 degrees. By comparison air temperatures varied 30-40 degrees. There were 9 out of 11 days with minimum air temperatures below 32F.

Jan 8-13 Max Min Max Min Cumulative Total
Range 68.9-39.5 37.3-16.3 49.0-44.2 47.9-42.1 0.74
Jan 15-19          
Range 73.3-35.2 43.7-19.6 48.1-41.4 45.4-41.3 0.78

Because the units can store only a limited amount of data and opportunities to retrieve it, there will be gaps in the data. In the near future, there will be a training session for docents to learn how to retrieve and record the data, so gaps in the data will be minimal.