Do you have any advice for purchasing an accurate thermometer so I can monitor the temperature at my house?
There are at least four key issues to consider when thinking about purchasing a thermometer set-up for reporting/recording daily temperatures:
(1) Instrument Quality: if you want reliable measurements, you need a good sensor system. Don't go cheap. And forget about those those "big dial" department store thermometers ... they are easy to read from across the courtyard, but can be up to 5 degrees in error!
(2) Sensor Capability: if you want to record daily highs and lows, you need a device that has storage capability to "save" the max & min ... unless you plan on checking the instrument about every two minutes all day long! ;-)
(3) Placement: where you put the temp sensor is actually more important than (1) and (2). A great sensor in a bad location is no better than one of those "big dial" tools!
(4) What are you trying to measure? This may sound like a silly question ("Jay, I'm trying to measure the temperature!") ... but in reality, are you trying to report a regionally representative temperature, or do you really just want to know how hot it gets on your backyard patio? These are truly two different questions. (Note that #4 is closely tied to #3.)
For regionally representative measures, carports, patios, backdoor and/or kitchen-window mounts, sides of buildings ... all of these are locations that tend to increase the "micro-climate" heatload. Even just being near a concrete or blacktop driveway can add a couple of degrees in the summer.
These are the kinds of problems that our Weather Watchers (WWs) must consider. You'll see WW readings that sometimes look to be a few degrees higher than the regional pattern suggests. In almost every case, "placement" is the culprit.
What do we test against? Normally, we look at the airport as a good site. Why? Let's face it: who lives at the airport, so how "representative" is that? We use the airport because the sensors are located in a wide-open, grass-covered area. Another great place is the LSU site at Ben Hur Farm (next to the LSU Fire School) -- also a wide-open area.
But wide-open is rarely an option .. unless you happen to be a farmer.
So ... you need an open, grass-covered space (even a dirt/clay surface gets too warm), as far away from buildings, trees, hardtop surfaces, etc., as is possible. Of course, for most of us (including me), our backyards aren't really big enough to find a "great" spot. But a so-so spot can be acceptable, if you're committed to getting the instruments.
Now ... cost: the bottom line for most of us. To do it right (or at least do it well and simply), temp sensors connected to your PC makes the process as trouble-free as possible. And I encourage interested persons to look into wireless instrument packages -- wireless transmitters greatly reduce the troubles of cabling and wires, and todays' wireless technology doesn't really add too much to the overall cost.
Still, this means being prepared to spend upwards of a couple hundred dollars to several hundred dollars. If you love tracking weather, it is worthwhile. But for the "occasional" interest, that may be a bit too large of a number to consider. Do a little on-line searching ... you be almost overwhelmed by the number of companies and variety of options available.
My experience with these "at home" weather stations is extremely limited, and I don't have one that I promote as a favorite or as a recommendation. (Indeed, I do not have an "at home" weather station, although I do have a NWS rain gauge.) However, I will tell you that "Davis Instruments" is one company that is often recommended to me.
Hope this helps.