Grouping Weather by Zipcodes: Help!

Hi!

I'd first like to thank you all in advance for all the help you provide in this forum.

My challenge is that I'm trying to group Zip codes by like-weather regions. I've found a website that groups weather by the first 3 digits of the zipcode -- you can google "weather by zip code" and the site is Wunderground (attempting to replicate this site in excel).

I'm trying to replicate the above site in excel but in groups of 5. I have two challenges: I need help on a function that will group like-zipcodes by the first 3 digits, and once those are grouped into like-zipcodes, I need to be able to group that list by 5.

Example for zip codes beginning "913"
Group 1
(91301) Agoura Hills, California
(91302) Calabasas, California
(91303) Canoga Park, California
(91304) Canoga Park, California
(91305) Canoga Park, California
Group 2
(91306) Winnetka, California
(91307) West Hills, California
(91308) West Hills, California
(91309) Canoga Park, California
(91310) Castaic, California
Group 4
(91311) Chatsworth, California
(91313) Chatsworth, California
(91316) Encino, California
(91319) Newbury Park, California
(91320) Newbury Park, California
Group 5
(91321) Newhall, California
(91322) Newhall, California
(91324) Northridge, California
(91325) Northridge, California
(91326) Porter Ranch, California
Group 6
(91327) Northridge, California
(91328) Northridge, California
(91329) Northridge, California
(91330) Northridge, California
(91331) Pacoima, California
Group 7
(91333) Pacoima, California
(91334) Pacoima, California
(91335) Reseda, California
(91337) Reseda, California
(91340) San Fernando, California
Group 8
(91341) San Fernando, California
(91342) Sylmar, California
(91343) North Hills, California
(91344) Granada Hills, California
(91345) Mission Hills, California

Please let me know if you have any questions.

Best

Eh, I think I solved it. First grouped by like Regions due to similar weather, then ascended by zipcode. Naturally ascending them groups by first three digits, then grouped by 5 based of a combing function. Total around 8,200 groups (5 zipcodes per). Looks like it worked for my needs, thanks all !

Thanks for your help!