High-quality waterproof temperature sensor can be used to measure both air and liquid temperatures. It can operate in two modes.  One  mode sends alerts when temperature goes above or below your thresholds. And the second mode allows you to send data to a ThingSpeak channel for display and analysis. See here for directions on how to setup this free data channel.  

Temperature Alert comes with an extra long flat 6 ft power cord. Its high quality  temperature sensor has a temperature range from -55°C to +125°C (-67°F to +257°F), with accuracy of 0.5°C over recommended range of -10°C to +85°C. All readings outside this range are ignored: -30°C to +105°C or -22°F to +221°F

Multiple (up to 5) email addresses can be added to receive temperature alerts.  All or some of them can be used  to receive text notifications. See General FAQ  for details.

Email messages are limited to one per minute per sensor.

Each MySpool temperature alert is monitored by a free Central Monitoring Service. If a device fails two daily check-ins in a row, an email will be sent urging to investigate power and WiFi availability. 

All MySpool services are free.