11th cent. From Vulgar Latin tempus veranum "spring season." The ancient Latins did not sharply distinguish the spring and summer seasons as we do today and in Old Spanish verano meant spring and estío summer until after the Golden Age. For the etymology of tempus, see tiempo. Veranum comes from Latin ver "spring."
From Proto-Italic *wes- 'id.' From Proto-Indo-European *u̯es-r/n- 'id.'
Also the origin of the surname Verano.
Asturian veranu, Portuguese verão, Galician verán, Aromanian vearã, Romanian vară
Middle Irish errach "spring," Old Welsh guiannuin 'id.,' Old Cornish guaintoin 'id.'
Old Norse vár "spring," Old Frisian wars 'id.'
Old Church Slavonic vesna "spring," Russian vesná 'id.,' Czech vesna 'id.,' Polish wiosna 'id.,' Slovene vẹ̑sna 'id.,' Lithuanian vãsara "summer," Latvian vasara 'id.'
Ancient Greek ἔαρ (héar) "spring"
Armenian garown "spring"
Sanskrit vasantá- "spring," Avestan vaŋri "in spring"