Files handling and lists

[gonzo620]

I am trying to read a text file and add each row into an appropriate list, but my lists return empty

with open('cities.txt','r', encoding = 'cp1252') as fin: # opens file with read permission
    data = fin.read().splitlines(True)
    with open('cities.txt','w', encoding = 'cp1252') as fout:
        fout.writelines(data[1:]) # gives write permission and deletes the first line

    coldsummer = [] # these are empty lists that will be filled in later
    warmsummer = []
    coldwinter = []
    warmwinter = []
    
    for line in fin: 
        line = line.split('\t') # splits elements in line with a tab
        
        lat = line[0] # these assign variables to certain parts of the file
        long = line[1]
        city = line[2]
        
        lat_deg = int(lat[0:2]) # splices and converts these values to integers
        lat_min = int(lat[3:5])
        long_deg = int(long[0:2])
        long_min = int(long[3:5])

        if lat_deg > 66: # these if statements will fill in lists with appropriate values
            coldsummer.append(line)
            coldwinter.append(line)
        elif lat_deg > 35 and lat_deg < 66:
            if lat[5] == N:
                warmsummer.append(line)
                coldwinter.append(line)
            else:
                warmsummer.append(line)
                warmwinter.append(line)
        else:
            warmsummer.append(line)
            warmwinter.append(line)

with open('cities.txt','r+', encoding = 'cp1252') as f: # adds the first line back
    heading = 'Latitude\tLongitude\tCity\tProvince/State\tCountry'
    filedata = f.read()
    f.seek(0, 0)
    f.write(heading.rstrip('\r\n') + '\n' + filedata)

What am I doing wrong?