Is it automatically sunny in some places?

Question

in any game because I have seen every other weather condition naturally in the wild eg. Hail at Snowpoint city, Rain in the moor of Iccurus, and sand in desert resort.

Answer 1

Places in the overworld where harsh sunlight is in effect:

Emerald:
Routes 114, 115, 116, 118 (only when Terra Cave is there)
Sky Pillar (when Groudon is awakened)
Routes 129, 130, 131 (when Groudon is awakened)

Ruby and Emerald (all when Groudon is awakened):
Lilycove City
Mossdeep City
Sootpolis City
Ever Grande City
Routes 124, 125, 126, 127, 128

Sun, Moon, Ultra Sun, Ultra Moon:
Haina Desert (from 10:00 a.m. to 4:59 p.m.)

Sword and Shield:
Route 6 (always)
Random sections of the Wild Area (all day, random days)

Places in the overworld where extremely harsh sunlight is in effect:

Omega Ruby (all when Groudon is awakened):
Lilycove City
Mossdeep City
Sootopolis City
Secret Islet
Secret Shore
Secret Meadow
Routes 124, 125, 126, 127, 128, 129, 130

Source

Answer 2

Sunny in places where Groudon is in R/E. That is the only places I know that would be automatically Sunny.