Becuase I'm ignorant and ethnocentric, when you said 30....I thought you meant Fahrenheit, and thought you were INSANE for tanning in that weather. Heh.
Slather that Aloe Vera all over your body. I used to lifeguard, and I am Hitler's wet dream (blonde haired, blue eyed, VERY light skin) and would frequently forget SPF.
I bet you would get a decent tan with SPF 30 if you're light skinned.
Sorry honey- I know it sucks.