Boreal winter, boreal summer, still no entry

The terms are used of course, it's just that there is no entry or explanation of them.

Example

 The NECC has a pronounced seasonal cycle in the Atlantic and Pacific, reaching maximum strength in late boreal summer and fall and minimum strength in late boreal winter and spring. Furthermore, the NECC in the Atlantic disappears in late winter and early spring.^[2]

Here's how easy it is to explain it when using it.