Would it be extreme to go from south africa to alaska right away?

im going to south africa this summer, and right after that, my gradparents are bringing all the grandchildren to alaska. the timing is very weird and the trip to alaska is 3–5 days after im supposed to get back from south africa. how will the time difference affect me? also, how about the extremes in climate? im also an avid traveller and i would love to stay in south africa as long as possible. are there any flights that connect to get to alaska right from south africa?

p.s.: the south africa trip is very flexible, but the alaska trip is not at all.