DM: It's a simple matter to get Rainbow Dash free and untied. Though it does beg the question of how a bunch of cute critters were able to overpower our resident Barbarian...
Fluttershy: Did you fight them? Or...
Rainbow Dash: Just because I don't like animals much, that doesn't mean I'm gonna go all-out on them.
Fluttershy: Thank you. I really appreciate that.
Twilight Sparkle: Now that Fluttershy's back to normal, what does Rainbow Dash's Cutie Mark look like?
DM: It's still three butterflies, same as Fluttershy now.
Rainbow Dash: So there's TWO animal-language Cutie Marks in play? That's weird.
Twilight Sparkle: Let's fix you next, then!
DM: So it sounds like you'll be taking Rainbow Dash to Rarity.
Rarity: Yes, that might be wise. If all our scenarios are deteriorating cartoonishly quickly like Rainbow's did... then mine has the potential to be particularly catastrophic.
DM: You're learning delightful lessons on how NOT to do weather control.
It's sometimes funny how, for narrative expedience, events progress to the worst-case scenario over the course of a single day, if not a matter of hours, if not minutes.
How not to do weather control? Let’s see… melt the polar ice caps slowly but surely, make things unbearably hot in much of the world, create and spread super deadly storms, threaten much of life as we know it… either God or humanity needs to learn how not to do this depending on your point of view.
Don’t try to teach humans what to do. They’ll either ignore you entirely, or do the exact opposite just to spite you. Best to just leave them alone to their impending doom...
Or for more 'normal' bad weather, in my ponyfinder campaign I made a city that produced bad weather for the entire country, as it was more efficient (they basically farmed windigos with careful emotion control magic). I named it Clefthand and based it on Cleveland...Or at least an extreme version of https://www.youtube.com/watch?v=ysmLA5TqbIY
Yeah, weather control in the hands (er, hooves) of a novice can be nasty. Though there's still the question of how Pinkie killed all of Sweet Apple Acres in that same timespan...
(My headcanon is that she was just weeding. From a rock farmer's perspective, there were a lot of weeds that happened to be apple tree-shaped.)
She can only control the weather, not how intense the sun is. So there is a limiting factor beyond her control that would prevent her from turning Ponyville into a localized desert. Nothing, however, stopping her from creating tornadoes and gale-force winds... except the general need for more than one weather-pegasus involved in generating the windspeed. But considering she has magic, that's not necessarily as limiting...
See, my problem here is that Ponyville is home to a bunch of pegasi that know how to weather. Rarity could have just got them together to maintain things until Rainbow got her cutie mark back.
Don't forget that OOC, Rarity knows the marks have been switched but IC, she thinks this is her real mark. Rarity's player isn't much of a metagamer, so presumably she's playing Rarity as someone who really, genuinely wants to control the weather because she thinks it's her destiny.
Ah the sheer undiluted bullshit of the 8th level spell "Control weather"...
Gave my PC's a unstable staff that 1/week can cast the spell, at the risk if destroying the otherwise very useful staff... Expected the, to SAVE it for IMPORTANT moments but they tempt fate with it every week :D