Los Angeles in September

Merino or synthetic. Cotton holds the sweat and you'll smell it by day two.

SimondSIMOND Women's Travel 500 Merino Wool T-Shirt$49.99Shop at Decathlon →ForclazSimond Women's Merino Resist Long-Sleeve T-Shirt$45 was $69.99Shop at Decathlon →SimondSimond Men's MT900 Seamless Merino Wool T-Shirt$45 was $74.99Shop at Decathlon →CoalatreeQuick Dry Short-Sleeve T-Shirt - Unisex$34.30 was $49Shop at Backcountry →

Linen or thin synthetic, because a cotton tee soaks through by mid-morning and stays that way.

CotopaxiSolta Long-Sleeve Sun Shirt - Women's$59.50 was $85Shop at Cotopaxi →Outdoor ResearchOutdoor Research Astroman Long-Sleeve Sun Shirt - Men's$60.47 was $110Shop at Backcountry →SimondSimond Women's Alpinism Seamless Wool Long-Sleeve Shirt$40 was $59.99Shop at Decathlon →SimondForclaz Men's MT500 Merino Wool Long-Sleeve Shirt$50 was $84.99Shop at Decathlon →

Look for UPF 50 on the tag. Check the tag says UPF 50. A plain cotton shirt is closer to UPF 5, and less once it's wet.

Topo DesignsTopo Designs Sun Hoodie - Women's$74.25 was $99Shop at Backcountry →The North FaceThe North Face Adventure Sun Hoodie - Women's$48.75 was $65Shop at Backcountry →Outdoor ResearchOutdoor Research Astroman Full-Zip Sun Hoodie - Men's$94.50 was $135Shop at Backcountry →NikeNike ACG Solar Chase Dri-Fit UV Long-Sleeve Sun Hoodie - Women's$99.95Shop at Backcountry →

One pair for every two days, plus two.

SmartwoolEveryday Merino Thong Underwear - Women's$34Shop at Backcountry →SmartwoolEveryday Merino Bikini Underwear - Women's$34Shop at Backcountry →SimondSimond Trek 500 Merino Wool Backpacking Underwear Women's$29.99Shop at Decathlon →REI Co-opREI Co-op Women's Merino Hipster Underwear$29.95Shop at REI →

Trail runners dry overnight where boots take days, which is why most people prefer them on warm trails.

CraftCraft Women's Endurance Trail-Running Shoes$130 was $175Shop at REI →KiprunKiprun Kipride Women's Running Shoes$140Shop at Decathlon →KiprunKiprun Kipsummit Max Women's Trail Running Shoes$150Shop at Decathlon →ScarpaScarpa Ribelle Run Trail Running Shoe - Men's$116 was $179Shop at Backcountry →

Buy it used: REI Re/Supply sells gear like this for less. See used gear

Bring the pair you already walk ten miles in. Brand new shoes on day one is how the blisters start.

NnormalKjerag Shoe$109 was $140Shop at Backcountry →SaolaQuito Shoe - Men's$130Shop at Backcountry →SaolaEzo Shoe - Men's$83.96 was $120Shop at Backcountry →ScarpaMojito Bio Shoe$59.68 was $199Shop at Backcountry →

Get a heel strap. Slides come off on anything steeper than a sidewalk.

KEENKEEN Women's Bali Strap TG Sandals$69.73 was $110Shop at REI →TevaTeva Women's Outflow Closed-Toe Water Sandals$74.73 was $100Shop at REI →ReefReef Water Vista Higher Sandal - Women's$80Shop at Backcountry →ForclazForclaz MT500 Lightweight Packable Hiking Sandals$40 was $59.99Shop at Decathlon →

Polarized kills glare, but the tag has to say 100% UV separately, and that's the part your eyes need.

ZealZeal Isabelle Polarized Sunglasses - Women's$67.03 was $149Shop at Backcountry →Ray-BanRay-Ban Wayfarer Oval Polarized Sunglasses - Women's$171 was $244Shop at Backcountry →SmithSmith Era ChromaPop Polarized Sunglasses - Women's$113 was $189Shop at Backcountry →ZealZeal Bennet Polarized Sunglasses - Women's$59.60 was $149Shop at Backcountry →

Get a brim of three inches or more. It covers your neck and ears, which a cap never does.

PistilPistil Women's Tegan Wide Brim Hat$39.73 was $68Shop at REI →BrixtonBrixton Mitch Packable Sun Hat Tan, L/XL$48.95Shop at Backcountry →DAKINEDAKINE No Zone Sun Hat Black, L/XL$24 was $40Shop at Backcountry →Wild RyeEdith Brim Hat$32 was $40Shop at Wild Rye →

10,000mAh is about two phone charges, 5,000 barely gets you through one long day.

Top pickGoal ZeroGoal Zero Venture 75 Power Bank$120Shop at REI →BioLiteBioLite Charge 80 PD Power Bank$99.95Shop at REI →AnkerAnker MagGo Power Bank (10,000 mAh, Slim)$80Shop at REI →AnkerAnker Power Bank (30W, Fusion, Built-In USB-C Cable)$40Shop at REI →

REI members usually get 10% back on full-price gear. Membership is $30, once. How it works

65W or more charges a laptop. Anything smaller only keeps up with phones.

Peak DesignDual Slim Charger$64.95Shop at Peak Design →Peak DesignPeak Design 65W Dual Slim Charger$64.95Shop at REI →AnkerAnker Wall Charger (33W, 2-Port) with USB-C to USB-C Cable$25Shop at REI →AnkerAnker MagGo Wireless Charging Station (3-in-1, Foldable Pad) with Charger and USB-C Cable$100Shop at REI →

35 to 45 liters fits most cabins. Check your airline's size limit first. Most won't take much over 40L in the cabin.

Top pickMatadorMatador 45L Global Travel PackSee price15% off with CHRISANDSARAShop at Matador →PacsafeGo Carry-On 44L Backpack$180Shop at Backcountry →Osprey PacksOsprey Packs Archeon 30L Backpack$132 was $265Shop at Backcountry →MatadorMatador GloberiderSee price15% off with CHRISANDSARAShop at Matador →

Hard shell protects what's inside, soft shell squeezes into a tight bin, and either way check the size with wheels included.

CotopaxiCoraza Suitcase - Carry On$295Shop at Cotopaxi →SamsoniteHyperflex ∞ Carry-On Spinner$126 was $180Shop at Samsonite →SamsoniteFreeform Spinner$154 was $220Shop at Samsonite →ThuleThule Subterra Carry On Spinner Bag$400Shop at Backcountry →

15 to 25 liters.

CotopaxiConsuelo 22L Daypack$120Shop at Cotopaxi →MammutLithium 20L Daypack$135Shop at Backcountry →CotopaxiElqui 24L Daypack$100Shop at Cotopaxi →Osprey PacksOsprey Packs Arcane Large 20L Daypack Botanica$65.97 was $110Shop at Backcountry →

Look for an IPX8 rating. Anything below that is splash proof, not waterproof.

Nite IzeNite Ize RunOff Waterproof Phone Pouch$34.95Shop at REI →Peak DesignEveryday Case for iPhone 11 Pro Max$26.96 was $29.95Shop at Peak Design →Peak DesignEveryday Case for iPhone 11 Pro$26.96 was $29.95Shop at Peak Design →ChromeChrome Large Phone Pouch$25Shop at REI →

Get locks marked TSA approved. Security can cut anything else off to search your bag.

MatadorMatador BetaLockSee price15% off with CHRISANDSARAShop at Matador →KnackKnack TSA-Approved Lock$16Shop at Knack Bags →PacsafePacsafe ProSafe 620 TSA Accepted Luggage Locks$17.95Shop at REI →PacsafePacsafe ProSafe 1000 TSA Combination Luggage Lock$17.95Shop at REI →

It runs on Find My, so this one's for iPhones.

AppleApple AirTag (2nd Gen, 4-Pack)$95.99Shop at B&H Photo →eufyeufy SmartTrack Link (2-Pack)$19.99Shop at B&H Photo →AppleApple AirTag (2nd Gen)$29Shop at B&H Photo →

Going in the water, buy the 80-minute one, since 40 minutes is barely one swim.

BadgerBadger SPF 50 Adventure Sport Mineral Sunscreen - 2.4 oz. Tin$18.95Shop at REI →Sun BumSun Bum Mineral SPF 50 Sunscreen Face Stick$14.50Shop at REI →Blue LizardBlue Lizard Sport Mineral SPF 50 Sunscreen Lotion$14Shop at REI →Sun BumSun Bum Mineral SPF 50 Sunscreen Lotion$17.50Shop at REI →

Look for 300mg of sodium or more, because some of the biggest sports drink brands have almost none.

MaurtenDrink Mix 320 Caf 100$56Shop at Backcountry →MaurtenMaurten Drink Mix 320 Unflavored, 14 Single Serve Packets$51Shop at Backcountry →SaltStickFastchews Chewable Electrolyte Tablets - Box of 12 Packets$42Shop at Backcountry →SaltStickFastChews with Caffeine - 10 Count Packets$42Shop at Backcountry →

Picaridin at 20% works as well as DEET, and it won't melt your sunglasses or the plastic on your pack.

Ben'sBen's Eco Spray Insect Repellent - 30 Percent DEET$9.50Shop at REI →Adventure MedicalAdventure Medical Ben's 30 Deet Tick & Insect Repellent Pump$1.92 was $2.95Shop at Backcountry →Adventure MedicalBen's 30 Deet Tick & Insect Repellent$1.92 was $2.95Shop at Backcountry →Ben'sBen's Insect Repellent Wipes - 30 Percent DEET$7.95Shop at REI →