to hail, for hail to fall (see Molina and Karttunen)
See an image that represents tecihui in the Visual Lexicon of Aztec Hieroglyphs, ed. Stephanie Wood (Eugene, Ore.: Wired Humanities, 2020-present).
4 Tecpatl 1547 Ypan teciuh iztac tepetl (p. 717)" = "4 Flint-knife (year) 1547. In this year it hailed on the white mountain" (Anales de Tlaxcala, no. 1, 1453–1603)
"1548 4 Tecpatl inpan onteciviloc in oncan ipan iztac tepetl (p. 984)" = "1548 4 Flint-knife (year). In this year it hailed there on the white mountain." (Anales de Diego García, 1502–1601)