There are infinite reasons for drop in Organic visits towards your website. Going through the checklist of top reasons might help you find the reason faster.
Find below few reasons for drop in website traffic. (Do mention in the comment if you have more):
Website was down:
Issue: If your website was not opening for certain period, then there would no visits during the same period. This could have happened because of server load, server down etc.
Find it out: In Google Analytics, Go to left side bar: Audience > Overview On the right side, select Hourly and get the hourly report for your website. This will display the visits on an hourly basis. You can compare the hourly visits for the specific days which you are comparing.
Google Analytics tracking code got removed:
Issue:The Google Analytics tracking code got removed from your website. This could happen during some changes being done on the website and the code got removed accidently.
Find it out: In the source code of your website, search if the analytics code is present.
Issue: During festivals and public holidays, people tend to surf less on the internet as compared to a working day. This is not more of an issue, but to balance out this traffic, you can concentrate on running campaigns which target these festivals. However, if you have a restaurant or entertainment related website, then public holidays are your peak days.
Find it out: For major festivals, traffic drop is expected. But for periodic festival like Christmas eve, the drop should be experienced moreover during the evening time. To find this out you can refer the hourly report.
Keyword Ranking gone down:
Issue:Search engine rankings for your keywords have dropped, due to which Search engine users do not tend to click on your website. Major clicks are achieved by websites which rank on 1st 5 positions.
Find it out: In Google Analytics, in the right sidebar, go to Traffic Sources > Sources > Search > Organic. By default Primary Dimension is Keyword, select the secondary dimension as Landing Page. Select Sort Type as Absolute Change. (This sort type can be selected only if you are comparing 2 time period/dates). Sort Visits in ascending order. This will display keywords and its corresponding landing page with highest drop in traffic. Although, virtually you cannot find keyword ranks through Google Analytics, but checking ranks of keywords with the most visits drop might help you to figure out whether there was any effect of keyword ranks on the traffic.
Visits towards few landing pages gone down:
Issue:There could be few pages on your website which have experienced drop in traffic. This could be due to removal of interlinking across the website, decreased backlinks, page completely removed from the website.
Find it out: In Google Analytics, in the right sidebar, go to Traffic Sources > Sources > Search > Organic. By default Primary Dimension is Keyword, change it to Landing Page. Select Sort Type as Absolute Change. (This sort type can be selected only if you are comparing 2 time period/dates). Sort Visits in ascending order.
Hope these reasons help you while analyzing the traffic drop for your website. And if it didn’t and you found out some other reason for the visits drop then do mention in the comment section!