I would not have it doing the alerting.
I'd have something poll it and graph the temp so you can see a good graph of room temp over time.
And have that same something do the alerting.
But do your servers have sensors too? You really need to monitor those as well because there can be a huge difference in room temp and server temp, and there is not always a good coorelation between them.
Munin is a good program for graphing and it has limited alerting that would be sufficient for this.