I knew the weather was heating up, but cardboard boxes on recycling day alerted me to the actual arrival of summer in Maine. Along the curb of a single Portland block, I spotted discarded packaging from: a Weber gas grill, a hibachi and a Big Green Egg. If I were a betting man, I’d wager that nearly every one of those new barbecues has already been used to cook a perennial American favorite: the hamburger.

Home cooks aren’t the only ones getting into the spirit of the season. Local restaurants, too, are tweaking their menus to make space for summer’s fresh produce, as well as a proliferation of patties.

It’s not just tradition – there is something about sultry weather that contorts our palates, making grilled protein and toasted buns even more appealing than they were in the cold.

When my editor told me that I had to taste six of Portland’s best burgers in a week and a half, I didn’t argue. I had seen the forecast.

Eat enough hamburgers, and you start to see how varied, how individual they can be. Every time I sampled a new one, I thought about its unique identity. Then during one meal, it hit me mid-bite, juice dripping onto a sheet of wax paper: Burgers are like people. Each has a unique character, inherited from those who created it. Some you like, some you don’t, and that’s okay.

What’s more, burgers – like people – can be messy. But secretly, that’s one of the things we love most about them.

With that in mind, the following list is a field guide to a half-dozen of the city’s finest burgers, categorized by personality.

You may see a few you know well, and perhaps a few you do not. Either way, summer is all about getting out while the weather is nice and making new friends. If some of them happen to be hamburgers, all the better.

THE MIDDLE CHILD

Nosh Kitchen Bar, 551 Congress St. Sweet + Spicy Bacon Cheeseburger. $12

Bookended on the menu between exhibitionistic stunt burgers and an unfussy cheeseburger sits what might be Nosh’s best sandwich. Here, the hot peppery mule-kick from sambal mayonnaise plays off sweetness from grilled onions that taste like they came from grandma’s pot roast pan. That back-and-forth distracts your tongue just long enough for the savory elements – white cheddar cheese and slightly chewy strips of smoky bacon – to sneak through alongside a little char from the flat-top grilled patty.

THE TRADITIONALIST

Mash Tun, 29 Wharf St. Grass-fed Burger. $6

This burger tops the restaurant’s no-nonsense food menu, and with good reason. Served “cooked through” (which in practice translates as medium), a thick beef patty is slipped into a toasted brioche bun with two simple garnishes: tart pickled onions and a slice of tomato. Execution matters when your signature dish has only four components, and Mash Tun nails it nearly flawlessly – even the dismount.

There are also 27 taps serving both beer and wine in this unassuming little wood-and-brick space, anchored by an antique cast-iron cash register bolted into a chunky wood bar.

When I asked for my check and remarked to the bartender that theirs might be the best value burger in town, he said, “I’m glad you liked it. Are you going to tell people about it?” I smiled, still anonymous, and replied, “You have no idea.”

THE GAMBLER

East Ender, 47 Middle St. House Smoked Burger. $14

Instead of ordinary ground beef, chefs Karl Deuben and Bill Leavy deploy a combination of cold-smoked chuck roast and short rib in their uncooked patty. Grilled to order and served with jack cheese and mayonnaise, the result is a burger that looks all-American, but smells and tastes like it spent a few formative summers with its meat-smoking cousins in Montreal. It’s a big risk, but one that pays off in sheer depth of flavor.

Even the accompanying pickles possess, as our server explained, “the sort of taste that people seem to either love or hate,” thanks to the inclusion of cloves in the brine.

Perhaps the plate’s safest bet is its Heston Blumenthal-inspired, thrice-cooked fries: exactly as ultra-crisp and browned as you’d expect from something simmered until starchy and tender, then deep-fried twice.

THE SELF-IMPROVER

Woodford Food & Beverage, 660 Forest Ave. The Burger. $16

Meticulous tinkering is responsible for the slow evolution of this burger, which has been on the menu since the restaurant opened early last year. Each new iteration brings the combo of brisket-blend patty, housemade pickles, grilled red onions and sharp Dijonnaise closer to the Platonic ideal of a hamburger.

Chef Courtney Loreg and her team even work collaboratively with baker Atsuko Fujimoto at Ten Ten Pié to nudge the bun recipe ever further toward perfection.

Bonus points for long, thin, spice-dusted fries that taste of salt and crushed fennel seed.

THE ONE WITH DIETARY RESTRICTIONS

LFK, 188A State St. LFK Veggie burger. $10

In place of beef, this patty is made with a textured blend of red lentils, crunchy panko breadcrumbs, leeks, bulgur wheat, cashews and mushrooms – an entirely unmeaty combination of ingredients. And that’s fine. Its goal is not to fool your mouth into thinking you’re eating beef, but to show you that you have options.

The flavors, from a little dill-tahini spread on the inside of a toasted poppy seed bun from Rosemont Market, to (if you’re feeling not-so-vegan) a savory slice of Swiss cheese, balance one another beautifully. This one is not just for herbivores.

THE OBSESSIVE

BRGR Bar. 11 Brown St. Oo-Mommy burger. $14

If you take a seat in this new Old Port restaurant, among the street mural-style artwork and buzzing neon, and take a bite of this sandwich, the world will telescope around you in tight focus. That’s because nearly every element of this burger, from the pudgy, six-ounce “aged primal blend” patty from Maine Family Farms, to pungent aged Gorgonzola, to bacon-onion jam, is designed to amplify a single flavor experience: umami.

The glossy, butter-brushed brioche bun is a little slippery, and the deep-fried, Pabst Blue Ribbon-battered onion rings slide immodestly out of the burger as you eat, but you won’t care about any of that. You’ll be able to concentrate on just one thing: what is in your mouth.

Andrew Ross writes the Dine Out Maine restaurant reviews for the Maine Sunday Telegram. He has written about food in the United Kingdom and in New York, where he co-founded NYCnosh, a food website. Contact him at:

andrewross.maine@gmail.com

Twitter: @AndrewRossME