Hey Google! What Ya Doing?
Here are a collection of web rank tracking tools that monitor how volitile (or not) Google is with its rankings.
Generally these tools sample many hunddreds or thousands of keywords and track who is ranking formthem and how those rankings change over time.
This is a good way to monitor for any Google Updates, as any changes will tend to affect many sites, where as a single site focusing on SEO and improving it’s rankings will not cause a Google Update alarm.
Weather provided by MozCast
Here are some other sites who provide data on Google rank-fluctuations…
Algoroo: Monitors Google.com and Google.com.au
AccuRanker: Monitors US, UK, Netherlands and Australia
SERPmetrics: Looking at Google and Bing US only.
SEMrush Sensor: One of my favourates as you can dig deep into your specific market sector. Covering US, UK, Germany, Spain, France and Australia.