There are 3 books in the The Winterlong Trilogy series. The newest book is Icarus Descending which came out in 1993.

1
Winterlong

Book cover of Winterlong
The “sensuous and evocative” debut of the Nebula Award–winning author of Waking the Moon: A dystopian journey through a world unburdened by moral taboos (Library Journal).
 Set in the surreal, post-apocalyptic City of Trees, Winterlong centers on Wendy Wanders, a girl who can tap into the dreams and emotions of…
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2
Aestival Tide

Aestival Tide
Four hundred years after the Third Shining, Hobi, Reive, Tast'annin, and Nefertity prepare for the prophesied collapse of Araboth, the domed city-state presumably protecting its citizens from the alleged horrors of the Outside

3
Icarus Descending

Icarus Descending
The energumens, creatures who are the result of centuries of genetic engineering, threaten to come to Earth to lead the other bioengineered slave races in a war against humanity