Arizona weather is hot and sunny, winter is a little cooler but generally year round VFR weather. In the mountains there is snow and cooler weather. Winter time, day temps up around 19-25, night temps 0-10. Summer, day temps 35-45, night 25, but itīs a dry heat!
Plus, Arizona doesnīt do daylight savings, so you can still get night flying at a decent hour in the summer. The school where I trained in AZ doesnīt do Visas, but maybe someone else can comment on other schools.