I had a really long post at one time about season changing routines. Let me try to paraphrase it.

1. In summer, you need moisture to combat/balance out humidity. You don't want the moisture level in the air to be more than than in your hair or your hair will "reach out" (frizz) toward it.

In winter, you need moisture to replenish what the extreme temps (cold and heat inside) with so much lower humidity in the air (so it's pulling humidity from your hair) are doing to dry out your hair.

2. In summer, just like you use lighter lotions on your body and more liquidy products rather than heavy creams, fluid is better on the hair. You don't want to suffociate it (read: crimped frizz) but balance its moisture level with its surroundings. In summer, I might just leave-in 10% of my conditioner during the rinse cycle so it's liquidy and dilluted and not too heavy.

In winter, you want to prevent moisture from being removed from your hair by the dry air. Therefore, rich creams, creamy leave-ins, and the like are perfect. I get a lot of frizz from creams in summer, but in winter, they give me chunky, clumpy, happy curls (like from the humidity's moisture but more in control). I'm more likely to use a cream or creamy leave-in in winter successfully.

3. In summer, the cuticle is more likely to absorb everything around and on it because the heat/humidity expands its "opening." Because of this, clarifying is more important. There was a curly who posted about a road-construction site near her work. She said it wasn't a problem in winter, but when summer hit, her hair smelt and felt tar-like, as if it was absorbing all that mess. It was heavier in the air too (riding upon the humidity's water particles in the air). Therefore, she clarified more often, and the problem was improved upon.

In winter, your cuticle is tighter (read: cold contracts instead of when heat expands). That's good for environmental yuck not penetrating. And because the air is drier (cold air can't hold as much humidity and inside's heated air is quite dry), you don't want to have to clarify (read: removes moisture) from your hair if you don't have to. Therefore, be careful about the creams you choose. Don't select creams that buildup because they will require more frequent clarifying (like summer's frequency), but the air is drier and can cause a vicious cycle (need more cream, need more clarifying, more dry so need more cream). A rule of thumb is that if you can't rinse a product easily from your hands with cool water (requires soap and/or hotter water), proceed with caution. And then clarify less often.

4. In summer, use a gentler poo since you want to avoid having to add creamy/heavier moisture but need moisture to combat the humidity.

In winter, it's fine for many to use a sulfate-containing poo to aid in the removal of the creamy leave-ins and creams without requiring full-fledged clarifying. You might not poo every day (maybe every other or third or once a week), but the pooing is a little stronger than summer to get the thicker stuff dissolved.

5. Here's what you've been waiting for...product suggestions.

In summer, for shampoos, I like Jessicurl HCC, Jessicurl Gentle Lather poo, and other sulfate-free poos. For conditioners, I like Jessicurl Too Shea and other cone-free conditioners with some weight to them that rinse clean. For those with finer hair, Suave Coconut Conditioner, Alba Botanicals Hawaiian Mango Moisturizing Hair Conditioner, Avalon Organics Awapuhi Mango Moisturizing Conditioner, and Aveda Shampure Conditioner. Also, Biolage Conditioning Balm, MyHoneyChild HoneyNutt or Jamaica Island Conditioners, Nature's Gate Organics Persimmon+Rose Geranium Moisturizing Conditioner, and VO5 Moisture Milks Conditioners are all good choices. For stylers, I like HE Set It Up, BRHG, Devacurl Angell, Back to Nature Rosemary Mint Clean Gel (smells divine too!), Ouidad Climate Control, and my end-all combo...a generous helping of Jessicurl RR with about a 1/4 of the RR amount of CCSS (this even survives FL's afternoon t-storms that happen most afternoons and the steaminess afterward).

In winter, for shampoo, I use Jessicurl Gentle Lather poo to start out with (like a transitionary poo), and then move on to Elucence Moisture Balancing Shampoo, Dove Moisture Rich Color, Suave Coconut, HE Hydrating Shampoo, Nexxus Therappe Shampoo, and many, many others. As long as it doesn't feel dry in my hair (Kenra poos were very drying for me), the sky is the limit. For conditioners, Elucence MBC, Nature's Gate Hemp Conditioner, Regis Smoothing or Olive Oil Conditioner, Umberto Giannini Curl & Twirl Detangling Conditioner, and countless others...winter is so wide-open since cones can come back on the scene without risk of being too heavy-yucky with summer's open cuticle. For stylers, I love Rusk Being Gutsy, Boots Curling Cream, AG Recoil, Sally's generic PM the Cream (regular PM the Cream recently changed the ingreds and I haven't gotten to try it), Ouidad Tress F/X, HE Totally Twisted Gel, Rusk Jele Gloss, CK under B&A BioMineral Gel, and Pantene Curl Defining Scrunching Gel on dry hair to smooth any strays.

HTH and hope I remembered everything!