ColdMac 9



Logging Started On: Dec 1st 2019
Logging Stopped On: May 6th 2020

Ambient Temperature High: 85.4° F
Ambient Temperature Low: 7.0° F

Relative Humidity High: 85.8%
Relative Humidity Low: 19.2%

Dew Point High: 65.6° F
Dew Point Low: -3.4° F

Processor High: 140° F
Processor Low: 32° F

Northbridge High: 149° F
Northbridge Low: 61° F

Logic Board High: 118° F
Logic Board Low: 32° F

Hard Drive High: 120° F
Hard Drive Low: 45° F
From to Now

Ambient Temperature High: ° F
Ambient Temperature Low: ° F

Relative Humidity High: %
Relative Humidity Low: %

Dew Point High: ° F
Dew Point Low: ° F

Processor High: ° F
Processor Low: ° F

Northbridge High: ° F
Northbridge Low: ° F

Logic Board High: ° F
Logic Board Low: ° F

Hard Drive High: ° F
Hard Drive Low: ° F

Database Stats

Records: 1,198,345
Size: 70.4MB

Mac Specs

Machine: Early 2009 iMac 20"
Processor: Intel Core2Duo 2.66 GHz
GPU: NVIDIA GeForce 9400
Hard Drive: 500 GB
Wifi: 802.11 a/b/g/n
OS: Mac OS X 10.11.6 (El Capitan)
Server: Apache / PHP / MariaDB

Official “Limits”

Operating Temperature: 50° to 95° F
Storage Temperature: -40° to 185° F
Relative Humidity: 5% to 95%
-° F
-° F
Dew Pt
-° F
-° F
-° F
-° F
Hard Drive

Alert! This web page has lost contact with the server, and as such, the values on this page are no longer live.

Please note, you do not need to reload the page. Just sit tight and this page will automatically reconnect to the server once it's back up.

Coldest Day of the Season - February 15th, 2020

Daily Temperature Range:

About This Mac

Don't reload this page! This site uses slick, modern web technologies to update all of it's content dynamically, in real time. No need to ever reload the page.

ColdMac is an old Apple computer that lives in my shed and tracks its own internal and external temperatures, and also hosts this webpage displaying that data.

The shed this Mac lives in is very cold. It is not insulated, the door has no seal, and there are two vents in the walls. So while there is a very limited amount of thermal protection, it's generally within 5 degrees or less of the actual outside temperature at night. During a sunny day, the shed can warm up much warmer than the outside temp.

This Mac is a 2009 iMac. It is loaded with internal thermal sensors. In addition to that, I use a USB thermometer to get ambient readings inside the shed. In total there are 7 values I picked as the most interesting. They get logged, displayed and graphed.

The design of the system can be broken down into two halves. A simple script runs every 10 seconds that gets readings from all of the thermal sensors, and loads them into a database. On the other side, this web page pulls that data out of the database and displays it accordingly, showing the current readings, a graph of the last 24 hours, and a graph of the daily high and low for the whole season. There is a lot of javascript that makes the dynamic content happen. But in the end, the database is what makes this possible.

In addition to running all web server related software, this machine plays music on loop 24 hours a day, and runs BOINC science projects at 15% CPU load, just to keep it busy.

Previous Winters



For questions, comments, suggestions, and general feedback, you can contact us via: