According to the Google examination of over 100,000 drives, low and moderate temperature don't influence the life expectancy of disk drives. Certainly if you keep the internal temp below 45C, there's virtually no effect, and only the slightest of effect for above 45C. That doesn't mean go above the rated temp, however.
Every drive you own should have environmental specifications available from the manufacturer giving you details on the minimum, maximum and sometimes the recommended operational temperature, as well as details on humidity and shock. Go check out the manufacturers spec sheets.
Alfredo Milani Comparetti's awesome Speedfan can "access status info from EIDE/SATA/SCSI drives showing...internal data that can be used to diagnose current and future hard disk failures". Essentially it will give you a reading of your drive's SMART status contextualised with real data from other users' disks, providing some interesting aggregated results.
For example, my for my laptop disk:
Your hard disk is a ST98823AS with
firmware 3.14.
The average temperature for this hard
disk is 41C (MIN=28C MAX=55C) and
yours is 51C.
...
Your hard disk is not below any
attribute threshold. This is good.
Your hard disk was never below any
attribute threshold. This is good.
...
NOTE : your hard disk has 23 reallocated sectors...
The final stats show my drive ain't looking so good these days :)
The overall fitness for this drive is
88%.
The overall performance for this
drive is 97%.
Note that Sean's answer correlates to the max value listed on Speedfan's hard disk temperature page, and that the results from that tool are aggregated observations only etc etc.
The operating temperature range for most Seagate hard drives is 5 to 50 degrees Celsius. With our newer model drives the maximum temperature is now at 60 degrees Celsius. ...
The drive should never exceed [these] temperature ranges...
Google and Microsoft have both done studies on disk drive temperature in their data centers. Google found that temperature was not a good predictor of failure, while Microsoft and the University of Virginia found that there was a significant correlation.
After looking at data on over 34,000 [of our] drives, I found that overall there is no correlation between temperature and failure rate.
[However,] all of [our] drives are well within the 0° (or 5°) to 60° that the manufacturers specify for the drives. And almost all of the drives are in the nice comfortable range from 15° to 30°.
[Also,] one drive [(the Seagate Barracuda & Barracuda LP 1.5TB)] does show some correlation between temperature and failure rates. The correlations of 0.17 and 0.11 are weak, but they are statistically significant. ... The failure rate of the ST31500541AS does go up at higher temperatures [that are nevertheless within the range of temperatures experienced by our drives.] This contrasts with most other drives we have, which don’t show that trend.
Although every drive will list its minimum and maximum temperature I believe that most if not all drive manufacturers design their drives to work at an 'ambient' temperature - i.e. out in the open in a regular office or home environment. Now obviously this isn't going to take into account of working in an Egyptian summer or an Antarctic winter but the point I'm making is that they don't actually NEED to be too cold, if you're comfortable with the temperature then your disk is too.
A few have said that they shouldn't get too hot, and that's very true but I was really surprised recently when I discovered that disks can actually be too cold. We have a lot of HP EVA FC-SANs and some of them have their 1TB 'FATA' disks in them. Turns out that these don't like being below about 18 degrees C, they switch into a 'read after write' mode that affects their performance. There's a new disk firmware out to hopefully fix this but it's the first time that I've seen a disk complain about being at such a warm, yet cold, temperature.
Basically i think drives will work best between 20C/68F (or 22C) and 35C/90F. The one thing I did notice that higher temps will usually cause ECC errors and other errors as well. I believe my 2TB HDD that has been on for about 4 years (2-3 years constant) was around in the 30C range.
The hours that the drive is on is most likely the biggest factor. I have an 80GB drive that is just starting to produce errors and it's avg temps are around 44C. I'd say the best way to keep your drives cool is to just to get a case with front fans leave the ambient temp around 70-76F and you should be fine.
According to the Google examination of over 100,000 drives, low and moderate temperature don't influence the life expectancy of disk drives. Certainly if you keep the internal temp below 45C, there's virtually no effect, and only the slightest of effect for above 45C. That doesn't mean go above the rated temp, however.
According to Jeff Atwood... hard drives are typically rated to run up to 55C.
Great post on this topic here: Hard Drive Temperatures: Be Afraid
Every drive you own should have environmental specifications available from the manufacturer giving you details on the minimum, maximum and sometimes the recommended operational temperature, as well as details on humidity and shock. Go check out the manufacturers spec sheets.
Alfredo Milani Comparetti's awesome Speedfan can "access status info from EIDE/SATA/SCSI drives showing...internal data that can be used to diagnose current and future hard disk failures". Essentially it will give you a reading of your drive's SMART status contextualised with real data from other users' disks, providing some interesting aggregated results.
For example, my for my laptop disk:
The final stats show my drive ain't looking so good these days :)
Note that Sean's answer correlates to the max value listed on Speedfan's hard disk temperature page, and that the results from that tool are aggregated observations only etc etc.
Some additional data points not mentioned in other answers:
Seagate says:
Backblaze says:
Although every drive will list its minimum and maximum temperature I believe that most if not all drive manufacturers design their drives to work at an 'ambient' temperature - i.e. out in the open in a regular office or home environment. Now obviously this isn't going to take into account of working in an Egyptian summer or an Antarctic winter but the point I'm making is that they don't actually NEED to be too cold, if you're comfortable with the temperature then your disk is too.
A few have said that they shouldn't get too hot, and that's very true but I was really surprised recently when I discovered that disks can actually be too cold. We have a lot of HP EVA FC-SANs and some of them have their 1TB 'FATA' disks in them. Turns out that these don't like being below about 18 degrees C, they switch into a 'read after write' mode that affects their performance. There's a new disk firmware out to hopefully fix this but it's the first time that I've seen a disk complain about being at such a warm, yet cold, temperature.
Basically i think drives will work best between 20C/68F (or 22C) and 35C/90F. The one thing I did notice that higher temps will usually cause ECC errors and other errors as well. I believe my 2TB HDD that has been on for about 4 years (2-3 years constant) was around in the 30C range.
The hours that the drive is on is most likely the biggest factor. I have an 80GB drive that is just starting to produce errors and it's avg temps are around 44C. I'd say the best way to keep your drives cool is to just to get a case with front fans leave the ambient temp around 70-76F and you should be fine.