python list comprehension: making list of multiple items from each list within a list of lists

Question

I have a list of lists, each with four items. For each list within it, I want to take indexes 0 and 2, put them in a list, then put all those lists in one list of lists. So, using for loops, I got what I wanted by doing this:

finallist = []
for i in range(len(weather_data)):
    templist = []
    templist.append(weather_data[i][0])
    templist.append(weather_data[i][2])
    finallist.append(templist)

so that gets me a list like [['2018-02-01', -18.6], ['2018-02-02', -19.6], ['2018-02-03', -22.3]]. But for this assignment, I'm supposed to do that by using one list comprehension. Best I can get is this:

 weekendtemps = [x[0] for x in weather_data if (x[1] == "Saturday" or x[1] == "Sunday")]

But that only gives me [['2018-02-01'], ['2018-02-2'], ['2018-02-03']]. How do I get both weather_data[0] and weather_data[2] using list comprehension?