Skyscanner
Skyscanner is a unique site that caches all the user searches so you can see some deals that others have found without actually having to click on the “Search” button.
If you know your dates, you can search directly, but you can also use their month-long search to see deals from a broader perspective.
Navigate to Skyscanner and input your departure & arrival city codes.
Enter your dates if you know them. Then enter the # of travelers and class.
If you want to use the month long search, click on the departure date and click “Whole Month”
Then click “Search”
You’ll see a view like this that helps you find the cheapest dates to travel.
*Remember this is cached search data, so if the fare is BRAND NEW, it likely will not show up here, and in that case refer to google flights.