I'm building a map for a tabletop RPG (Pathfinder specifically), the aim of which is that my players will be trekking around and visiting interesting places. As part of that, I'd love to portray a bunch of exotic climates, such as deserts, jungles and tundra (to name a few). However, on Earth, the Tropic of Cancer and the Arctic Circle are almost 3,000 miles apart, which is a long way to force my characters to walk.

Thus my question, what rules do I need to follow, be it manipulating elevation, weather patterns, placement of oceans/mountains, etc, in order to bring my hot and cold climates as close together as possible?

As this is a fantasy world, some Suspension of Disbelief or magic can be used, but I want to avoid any jarring revelations as much as possible.

Mountains

In Peru (for example) Cusco is at 3400 meters elevation. The average year-round temps is 12 C, the average low is close to freezing, and it has historically been below freezing every month of the year. Frost and hail are common in all months (although snow accumulation is rare)

Meanwhile only 90 km away, is Pillcopata, Peru, at 500 meters, in the heart of the Amazon. Average year-round temps are 24 C; there is a mini-'winter' in May-July, but the other months have an average high of 30 C. It rains year-round, monsoonally in the summer, about 3000 mm per year, which is three times what New York City would see. It looks like this:

There are plenty of other examples around the world. Elevation will solve all your heat vs cold problems. Snowy mountain highlands can be just a day or two's travel away from steamy jungles. Other examples that I could have added would put cool temperate forests in the mountains above hot deserts (as in Central Asia or the southern Great Basin) or misty forested hills above sweltering fertile plains (like Sichuan province in China, or the upper Ganges Basin in India).

Geothermal springs can create a warm, lush forested region in the valley of a frozen mountain range, just as natural springs can create a large oasis in a desert. I suppose it would be possible for strong ocean currents to reliably carry large icebergs from a polar region to the beaches of a tropical region, and thus support cold-weather flora and fauna in the waters and on land year-round.

on Earth, the Tropic of Cancer and the Arctic Circle are almost 3,000 miles apart.

If you drop the jungle from the requirement, you only need to walk 1/3 of that.

You could wander from the Mojave desert in California all the way north to the temperate rain forrest from Washington. A little further north and you get tundra in British Columbia, I think.

If you still want that jungle you can handwave it with magic. Terraria and other videogames have underground jungles and nobody complains about that... Kinda adds to the whole magical and fantastic theme.

Have strange ocean & wind flows.

Possible causes for strange ocean flows :

• Extreme version of deep sea "volcanos"/smokers :
  

Possible causes for strange wind flows & climate :

• Astronomical configuration : have multiple suns, or multiple other planets leading to a complex lighting of your planet; some parts would receive more sunlight, thus be hotter, and others would be in the shadows. Your planet could also be small(or even a moon) and spin around strangely.



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  As already mentioned : Height differences

  
  
  
  
  
  • Expanding on this point : Mountain Ranges - Imagine a valley surrounded by high mountains. The climate in it can be totally different from the outside; for instance, rain clouds would be raining over the mountains and "filling" the valley
  
  
  
  

Bring the glaciers closer to the equator

Since you're not confined to Earth or Earth-like geological parameters, you can do whatever you want.

Ways to achieve close geographical proximity of wildly varying climate zones

• Bring the glaciers closer to the equator. While climate and ice sheets are linked, since we are designing a planet to do what we want. Just plunk down some ice sheets over the large land masses. This will increase the steepness of the thermocline from its maximum at the equator to arctic wastelands.


• Reduce the amount of atmospheric greenhouse gases. This feeds into the mass glaciation but also decreases the amount of heat that the atmosphere can hold.

Effects of these Changes

Since the glaciers come so far south/north, they push the tundra ahead of them. This overall compresses the distance required to go from tropical temperatures to arctic conditions.

At the equator, start with lush jungles. Temperatures are high because of the strong solar heating. Further north where solar illumination is weaker, temperatures start to cool. Temperate forests and cooler rain forests would appear in this zone. Still further north would be desert conditions where the descending air from the tropical Hadley Cell descends carrying relatively moisture free air. Beyond the warm dry zone, temperatures will continue to fall to tundra then arctic conditions.