I know weather impacts - but not sure how large impac storms will alter… don’t remember previous years.
Try Field Researches that reward Fire type Pokémon (Earn a Candy walking with your buddy, Evolve 5 Fire-type Pokémon…).
Do Fire type Raids (Moltres when available, Alolan Marowak [?])
Also go out during Sunny Weather, as Fire type Pokémon are way more common then (Vulpix, Numel, Sunny Castform…)
And not to forget: the Breakthrough Box reward Entei is also a Fire type Pokémon.
I didn’t actually think about a separate research task reward counting toward another research task… thanks!
Definitely target the “Earn a candy walking your buddy” task, put a Magikarp/Gyarados as your buddy & that’s only 1km to get that task done - try and get 3 of this task & get three times the benefit (that’s 3 Numel earned for walking 1km)
Also definitely hunt down the “Use 10 berries to help catch Pokémon” task - again try to get 3 of these at a time, if that’s even possible, that gives you Growlithe (which can also be a shiny!!).
It’s winter down here in NZ & so far September’s been either cloudy/partially cloudy or raining in terms of the game’s weather - very low on the fire type spawns - so I had to resort to this approach myself.