Google has released the deadline when Chrome will begin warning users if a site in insecure. This date is set to July 2018 and Google urges publishers to upgrade to HTTPS.
The warning that will show is displayed in the image below.
This could have a negative effect on your website traffic, because users might not feel secure on your website. First signs will be shown in the bounce rate of a web page.
Warning on Mixed Content?
It's not clear whether mixed content pages will trigger the warning. Mixed content pages are pages that are using the HTTPS but some pieces of content are still using HTTP.
Do you need to upgrade to HTTPS?
Seeing how Google is treating website with SSL and how it has been pushing website publishers to migrate to HTTPS, it is a good idea to upgrade as soon as possible.
Google has been giving subtle hints over de years that they want each website secured. This is another hint and they will make the ranking signal for SSL bigger in the future.
Most web hosting providers offer free or low cost certificates.