Weather

Observation history from our home in Janesville, Wisconsin

My son got me a small weather station for Christmas in 2008. It shows indoor and outdoor temperatures along with the current time, and it also displays maximum and minimum temperatures. Since I already measure snowfall here at the house, and I also have a rain gauge, I decided to begin posting temperature and precipitation records on this site.

Temperature sensor placement

At first, the sensor was located on the outside north wall of our house, near the front door. Sun exposure to the porch, mainly during mid- to late afternoon, caused false high readings, so I moved the sensor to a north-facing wall on the east side of the house, near the side door, on May 19, 2009. Though the porch would catch sun early in the day, this was normally after the morning low and before the afternoon high; I would reset the maximum index around 1 pm to avoid a false high reading from the morning sun exposure.

A neighboring house to our east served to block early morning sun from reaching the porch and the sensor. That house was torn down on September 24, 2013. I didn’t consider the effect of that demolition on my temperature sensor, but I believe that effect has increased a bit every passing year for some reason. By summer, 2019, I was starting to get consistently hotter high temperatures than expected. Just walking outside near where the sensor was, I could feel that it was hotter than anywhere else in the yard.

On July 28, 2019, at 3:00 pm, I experimentally moved the sensor back to the north wall by the front door. At that hour, the readings in both locations were identical, but soon the reading at the front door was soaring due to sun hitting the front porch. Finally, I got the idea to move it away from the house and porch altogether; later that same day, I relocated it to the north wall of the shed in our back yard. There is only grass in front of the shed, and buildings shade the sensor at all hours except briefly around 6 pm in summer. I watched as dappled sun danced around the sensor, and the temperature rose by just 0.5 °F. We should be good to go.

On July 30, 2019, I noticed that the early morning sun clears the neighboring house briefly, hitting the sensor. Readings were normalized by 9:15 am today and should be okay by 9:30 even at the summer solstice. This should not affect high temperatures which normally occur later in the afternoon and are much higher anyway; I can reset the index around 9:30 am if it’s sunny during summer. On cloudy days, and during other seasons, the sun will miss the sensor altogether.


Earlier precipitation figures are also available:

Find links to various weather resources at our Useful Links page.