Outside temperature sensor that can record data

November 2, 2015 2:20 AM

I want to know how cold a certain spot on my balcony gets during the night. How do I achieve this? Preferrably very low-cost and low-fuss and, of course, not having to get up during the night. The range measured would be -10C to +10C (14F to 50F), and although I don't need to know the exact temperature, it would be nice to have a number that is off by no more than a couple of degrees.

I only need the lowest measurement, so it doesn't matter if I get a series of numbers/a graph or just one number.

If it helps, I have an Android smartphone and a Windows/Linux PC, but lack any knowledge of (or interest in) Arduino and similar stuff.

I could just put a standard thermometer outside and then go outside in the night to take a look at it, but other family members would probably not be happy about being woken up by my comings and goings. But if I do go that way, when should I be checking out the thermometer to get the lowest temperature? At dawn?

posted by gakiko to Home & Garden (6 answers total)

There are actual thermometers that'll store lowest/highest temps. My parents have one - I cannot remember the make, sorry - and they've had one for years. Basically you just press a button and the thermometer will tell you the lowest temp over the last 24 hours.
posted by kariebookish at 2:32 AM on November 2, 2015 [1 favorite]

i have one of these which i use to keep track of the temperature of medication while travelling. it stores max and min temperature (which you can reset). they don't have a reputation for being hugely accurate, but mine has been fine - the error from comparing with other thermometers seems to be a degree or so (celsius).
posted by andrewcooke at 2:41 AM on November 2, 2015

You can go with something like this, or a wireless equivalent so you don't need to run a cable out to it.

The minimum temperature usually occurs just before dawn, but not always.
posted by jkent at 2:47 AM on November 2, 2015

There are apps for that. Search the Play Store for "temperature logger".

If you're using the temperature sensor inside your phone, you'll want to calibrate out the offset due to the phone's internally generated heat. That should be close enough to constant over the temperature range you're talking about, so a simple one-time comparison of the phone's current reading against a known-accurate thermometer at a temperature somewhere inside your target range should be good enough.
posted by flabdablet at 3:44 AM on November 2, 2015

If you do a search for gardening thermometer you can get one that will store min and max temperature, but wouldn't use any electricity at all, it just keeps a small mark in the tube, one for low and the other for high.
posted by koolkat at 5:24 AM on November 2, 2015

I used on of these in my greenhouse in England. Just $10 usd.
posted by srboisvert at 6:24 AM on November 2, 2015