Weather is baked into the DNA of Greyhawk, going all the way back to Dragon Magazine #68 (and subsequently, the Greyhawk Glossography). The Glossography appeared in the 1983 World of Greyhawk boxed set, and includes a full weather generation system. Almost every campaign I’ve run over the last 30+ years used that system, with the occasional story-based embellishments.
The Prompt
Day 7 – What’s the weather like today? Is there a particular climate or weather that’s prominent in the region of the campaign? Does it vary? What is it like and how bad does it get?
Visit Nuketown’s RPG Campaign Tour Challenge 2026 Prompts page for the rest of our challenge posts.
Summon Weather
While the first appearance of the Greyhawk Weather charts was in Dragon #68, my first exposure was the Greyhawk Glossography. The charts provide a high-level overview of weather in Greyhawk and includes a thumbnail map listing latitudes of the Flanaess (the central region where most of the campaign occurs) which corresponds to a North American climate. The weather generation tables allow you to create regional weather based on latitude, shifting the results appropriately as the regions get colder or warmer.
It also documents the phases of Oerth’s moons: Luna (similar to Earth’s moon) rotates the planet every 30 days. Celene’s orbit is much slower, taking 90 days to complete an orbit. The periods of the two moons lead to super full-moons, when both objects are full, as well as darkest nights, where both are new. Knowing the lunar cycles helps you describe night time scenes as the players inevitably post watches for their long rests.
While it’s fun to roll dice and look up results, it takes a lot of time to create a month’s work of weather. The Scroll of Weather Forecasting does the work for me. It has a bunch of options, including daily temperatures, sunrise and sunset, moon phases, precipitation types, and more. You can set the month, terrain, and latitude, and it will give the results in metric or imperial.
I generate my weather one to three months at a time, and store the results in a Google Sheet. Then I use that self-same sheet to document happenings in the campaign (e.g. rumors, notable events, when specific chapters happened in-game, etc.).
Greyhawk weather often plays a significant role in my game as it helps add flavor to what’s happening … as well as challenges. In a previous campaign, a blizzard led to a 3 or 4 session arc as the players fought through the snow to find refuge, then had to trek back to their hometown. Once there, a murder unfolded during the storm, leading them to slug from location to location investigating and trying to deal with the threat. Afterwards, the city dealt with the consequences of the freak storm, which destroyed many of its simpler wooden structures.
The Rains in Greyhawk Fall Mostly on the Plain
My Greyhawk ’76 campaign takes in Wealsun CY 576, which equates to low summer. It takes place on the Plain of Greyhawk and the surrounding hills and marshes, and lies at 35N° latitude. Temperates range from lows in the 60s (Fahrenheit) to highs in the mid-80s. Weather is typically pleasant, broken up by periodic rain (including a few intense thunderstorms).
The campaign spreadsheet includes several columns:
- Date
- Day
- High Temperature
- Low Temperature
- Precipitation (duration)
- Wind (from, speed)
- Phase of Luna
- Phase of Celene
- Campaign Chapter(s)
- Campaign Notes
This provides a heady way of keeping track of what happened when in the campaign, but just as importantly, it helps me look (and plan) ahead. I use the campaign notes column for quick recaps of the adventures, as well as future notes about what will happen.
Low Summer, High Drama
For the last month of the campaign the players have been trying to catch up with the Burrow Boys, a band of murderous halflings operating on the Plain of Greyhawk. Thanks to a secret note they intercepted, they know exactly where and where the gang members will be.
- Where: Swamp’s Fork, a criminal meet-up / flea market that appears periodically in the depths of the Mistmarsh.
- When: Wealsun 25
Nearly half of the campaign has been focused on them making it to Mistmarsh on time. While most of the weather they encountered didn’t hamper them, they did get caught up in a massive thunderstorm that formed the backdrop for a battle with an elder froghemoth named Glub-Glub.
As Wealsun draws to a close, they’ll head into the festival week of Richest, which includes the Midsummer Festival and the notable celestial event of Luna and Celene at their full moon phases. After that, they head into Reaping and the formal start of high summer. The weather will trend much warmer, which will bring with it more severe rain and wind storms.
It’s the perfect set up for a high summer show down with the Burrow Boys, which nicely complements the fantasy western tropes that we’ve been leaning into with the campaign.