Google rarely reports when they are making changes to the algorithm and responds to questions with a standard “we make changes to the algorithm constantly” or something along these lines. However, there are multiple tools and websites that monitor fluctuations in search rankings for a wide range of keywords. These tools clearly show when substantial changes have been made with movements of many keywords.
Around the 25th of June 2017 a number of these websites and tools were reporting changes to the algorithm. The below measurements are from Rank Ranger, SEM Rush & Accuranker and all seem to be reporting an update around the end of June as well as in the first week of July.
Have you noticed any changes in ranking or organic search traffic to your website? If you have dropped off in terms of traffic it might be a clever idea to look at the content on your website or the links that are pointing to your website. It is best to do an SEO audit of your links, content and technical aspects of the website when there are signs of trouble.