Name in Hieroglyphs:

Symbols: throne, rain, lion
Cult Center: Heliopolis
The goddess' name is related to the root tef, "to spit, be moist" and nu, "sky, waters". Appropriately, she was the personification of the moisture of the sky. Tefnut was the counterpart to Shu and the mother of Geb and Nut.
Tefnut and her husband Shu were the children of Atum who created them by masturbating. When Atum became associated with Re, Re became Tefnut's father. According to one myth, Tefnut became angry with her father Re and ran off to Nubia. The god Thoth went to find her and conjoled her into returning to Egypt.
Tefnut was depicted in the form of a woman who wears on her head the solar disk circled by two cobras. She holds in her hands the sceptre and ankh. Many times she has the head of a lioness or is shown as one.
FROM: Ancient Egypt: the Mythology - Tefnut

Patron of: moisture, warm air.
Appearance: a woman lying horizontally between the firmament and earth. Sometimes she is pictured helping her consort Shu hold up Nut.
Description: Tefnut, along with her brother Shu, was the first deity created by Atum in the beginning. She was the goddess of moisture (remember that even in ancient times, very little rain fell in Egypt) and of the warm moist air near the Nile. At one time she argued with her father and left Egypt for Nubia. Only Thoth could persuade her to return.
FROM: Touregypt's "Tefnut"

Main center of worship:
Mainly connected to the Ennead at Iunu/Heliopolis/Cairo, 13th N, Lower Egypt.
Nay-ta-hut/Leontopolis/Tell el-Muqdam,
11th Nome, Lower Egypt

Festivals: (exact dates not historically verified)
30th August - 13th Paopi - Day of Satisfying the Hearts of the Ennead
29th October - 13th Koiak - Day of Going Forth of Het-Hert and the Ennead
15th November - 30th Koiak - The Ennead feast in the House of Ra, Heru and Wasir
FROM:'s Thoth, Djehuti, Ta-tenen, Tawaret, Tefnut,

Other links:
Tefnut, Goddess of Moisture and the Moon, and Dryness and the Sun by Caroline Seawright (long article, has info) Names of Netjer : Tefnut
Tefnut summary
Tefnut Meeting (a guided meditation)
Beloved Netjer - My Lady, Tefnut (a personal site)
Ancient Egyptian goddess - Tefnut
The Gods of Heliopolis TEM, SHU, TEFNUT (touregypt)

Sites about her consort, Shu:
Egypt: Shu (God), Holder of the Sky, God of the Air, Wind, Sunlight and
Shu (Egyptian deity)
Ancient Egypt: the Mythology - Shu
Shu, Egyptian god of the air and supporter of the sky Names of Netjer : Shu