From Tolkien Gateway

Nénimë (Nínui in Sindarin) was the second month of the year in the Kings' Reckoning and the Stewards' Reckoning. In both calendars, Nénimë followed the month Narvinyë, preceded the month of Súlimë, and was 30 days long, lasting from the 32nd through the 61st days of the year. In the New Reckoning it was the eleventh month of the year.

Nénimë in the Kings' and Stewards' Reckoning corresponded to Solmath in the Shire Calendar (approximately modern 22 January through 20 February).[1]