Weather Station details

        view of weather station looking northeast
                 (click here for a winter shot)

Station accuracy

Wind readings:

Official wind readings are taken from well exposed airport sites at a height of 10 meters (33 feet)  Thus, wind readings from my site (half the official height and less ideal exposure) will be less than airport observations, usually by half. Wind gusts however may occasionally reach airport values.. especially in a southerly flow which has the best exposure at my location.  Westerly winds tend to be sheltered by my residence and are often underestimated. Wind readings are also better during October through May when surrounding trees are bare.   Full tree foliage will lead to lower overall wind readings during the summer months.    

Temperature:

The temperature sensor is housed in a radiation shield on the unit placed in full sun. Temperatures are generally quite reliable (within 0.5C of official readings).. especially on cloudy and/or windy days.  However during sunny, light wind days (especially in a light west or northwest flow), my unit will usually register readings that are about 1-2C too warm compared with official observations. This is most evident from late morning until late afternoon when the unit gets full solar radiation and there is little ventilation to mix the air surrounding the unit.  My backyard has a full southern exposure and will warm up considerably in sunny light wind situations. 

Humidity:

The humidity sensor is housed with the temperature sensor inside the radiation shield.  I have found humidity readings are quite reliable, often within 5-10% of official readings.  Most often, humidity readings tend to be a little higher than official airport observations mainly due to less ideal mixing.   Note that the dew point is calculated directly from the humidity reading.       

Rainfall:

Rainfall is the most variable parameter, and depends largely on the prevailing wind direction, and the intensity of rainfall.  Generally, I have found that the unit (a tipping bucket gauge) slightly underestimates rainfall ( by about 5-10%) compared to my nearby official weather service rain gauge.  The gauge will likely underestimate rainfall in strong westerly flows due to a sheltering effect from my house.  Note also that tipping bucket rain gauges tend to underestimate rainfall in high intensity cases.  My VP rain gauge is not equpped with a heater.. thus winter precipitation is not recorded.  Rain does not generally occur in this climate from November through March.  Rainfall season begins April 1st.