The sixth month of the Shire Calendar, lying between Thrimidge and the midsummer feastdays of Lithe, and approximately equivalent to modern June. In fact, it ran from modern 22 May to 20 June.
Midsummer was an important festival in the Shire Calendar, in which three days (or four in a leap year) were set aside as 'Lithedays' that fell within no month. The months preceding and following these Lithedays were named by the Shire-hobbits simply as Forelithe and Afterlithe (that is, simply, the months before and after Lithe). Of these, Forelithe ran from Hensday1 to Mersday30 (dates always fell on the same weekday in the Shire Calendar).
Forelithe was the name used for this month within the Shire, a name based on Old English ǣrra līða (where līða referred to the warm and gentle weather of this time of year. The tradition in Bree was to use the name Lithe for this entire month (and the days around Midsummer, which the Shire-hobbits called Lithe, were known as the 'Summerdays' in the Bree-land). The Forelithe of the Hobbits ultimately derived from the calendars of Men, in which it was known by the Elvish names Nárië or Nórui, names which, like Lithe refer to the warmth of the weather at this time of the year.
From the perspective of the Shire-hobbits, the most important historical event to take place in the month of Forelithe occurred in 1342 by their calendar (or III 2942). This month saw the sudden and unexpected return of Bilbo Baggins, who had disappeared without explanation more than a year beforehand (and had indeed been declared officially deceased). It was later learned that he had been adventuring in the East, accompanying Thorin and Company on the Quest of Erebor, and rumours of the fabulous wealth he gained from this endeavour began to circulate around the Shire.
Seventy-six years later, it was the month of Forelithe that saw the formal beginning of the War of the Ring, when Sauron sent probing attacks against Gondor and against the Woodland Realm in Mirkwood, but these events took place far from the Shire, and went unnoticed by the Shire-folk. The War was fought in earnest through the winter of that year, III 3018, and the spring of the next. With the War won, the Forelithe of III 3019 saw celebrations as Arwen travelled southward to Minas Tirith in Gondor, where she wed Aragorn at Midsummer. There were no such celebrations within the Shire itself, however, as it remained in the grip of Sharkey and his Men during most of this year, and it would not be until Blotmath (or November) that the Shire-hobbits would be freed from his control.
For the opposite season of the year, around Midwinter rather than Midsummer, the Shire-hobbits followed a similar arrangement for naming the months. Their Midwinter festival was known as Yule, and (following the same pattern as for Forelithe and Afterlithe), Yule was preceded by a month named Foreyule and followed by one named Afteryule.