Frizzy hair...help please?

i have just recently moved to an area where it is constantly humid in the summer. I have very frizzy, ugly-curly, wild and unmanageable hair. I usually straighten it and don't wash it for a couple of days, but when it it is humid outside, my hair immediately goes from perfectly straight to its naturally curly and frizzy texture, which is very unflattering on me and most likely everyone else. I'm here for the entire summer and if I have to deal with this hair for to months i'll go crazy...so what are some good products [that actually work] that will keep my hair straight, even in the humidity? its almost 80% humidity every week this week. also, products that make my hair shiny and not frizzy would be great too. thanks.