# Change mode when it's raining? **URL:** \ **Category:** Automation Ideas\ **Created:** [July 9, 2015, 2:48am UTC](https://community.smartthings.com/t/change-mode-when-its-raining/18937 "2015-07-09T02:48:35Z")\ **Posts on this page:** 1\ **Showing post:** 15
**Author:** ![JDRoberts](https://yyz2.discourse-cdn.com/smartthings/user_avatar/community.smartthings.com/jdroberts/32/56577_2.png) [@JDRoberts](https://community.smartthings.com/u/JDRoberts)\ **Post date:** [July 10, 2015, 3:47am UTC](https://community.smartthings.com/t/change-mode-when-its-raining/18937/15 "2015-07-10T03:47:58Z")
> [@Keo](#): > > I was looking at Netatmo, but I saw relative humidity not rain fall. I’m no meteorologist, so how would relative humidity tell me it’s raining. Sorry if this sounds like dumb question. Relative humidity is the amount of moisture the air can hold at its current temperature. Once the relative humidity gets to 100%, any additional moisture will then have to be released as either rain or dew. Or you could get fog. Since colder air can hold less moisture than warmer air, it’s really common for rain to form high in the sky where the air is colder, and then fall down through the warmer air to the ground. This is why relative humidity measured in your front yard might be 90% but it’s still raining. That’s because the rain formed higher up where the relative humidity _was_ 100% [http://wxdude.com/humidity.html](http://wxdude.com/humidity.html) As far as making the mode change, do you want it to change when there’s detectable rain at your house? Or just a forecast of rain? If it’s detectable rain, as others have said, any moisture detector can be the trigger–just understand that you’d get the same mode change for dew as well. So think carefully about how you want to use it. You can either use a sensor that communicates directly with ST, one that has an open API, one that has an IFTTT channel, or one that can send text notifications which you could have sent to IFTTT. --- _[View the full topic](https://community.smartthings.com/t/change-mode-when-its-raining/18937)._