Unless you want to buy an outdoor thermometer in a garden store or supermarket that is more decorative than precise, you should go to specialized stores or Internet sites to find precise and, if necessary, aesthetic materials. For weather stations and their temperature sensors, they can be found both in stores and on the Internet. But while stores only distribute a few brands, all brands are present on the Internet and prices can easily be compared. An outdoor thermometer to hang or stick on a glass pane is around $3 for a classic liquid marker thermometer but with very few guarantees on the reliability of its measurement. Dial thermometers with a metal spiral probe are even less accurate but are often at $ 1! From about $10 you can find power stations with a wired thermometric sensor and you have to count a little more than $20 to find radio-controlled thermometer power stations (wireless). Good to know: whatever type of outdoor thermometer you choose, think that in summer, the sun's rays can easily raise its temperature to damage it.