Regulating Growroom Humidity in Different Climate Regions

By Kent Gruetzmacher
Published: January 9, 2023
Presented by AC Infinity Inc.
Key Takeaways

When growing cannabis indoors, one of the most overlooked elements is the climate outside the growroom. It’s a good idea to know how much relative humidity is in the air outside as it will impact how your plants grow inside.

Being a skilled indoor grower requires more than a green thumb, you must also be able to adapt your approach to changing conditions and circumstances. No matter where you live, the outdoor climate will affect the ambient conditions of your indoor garden. Therefore, studying up on your region’s climate is important in fine tuning your cannabis grow and maximizing harvests.

Along with temperature and lighting, humidity is one of the most important factors to consider for indoor growing. Cannabis plants require very specific humidity levels to thrive and these levels change with different growth phases.

By knowing the unique demands of your region’s climate, you can implement the right technology to maintain ideal humidity levels for your plants.


What are Climate Regions?

Scientists have several classifications they use to describe different environmental conditions on the planet. While planting zones refer strictly to temperature gradients, climate zones delineate between different regions based on average weather conditions.

Due to the sheer diversity of landscapes in the U.S., we enjoy a number of climate zones. To illustrate, southern California and Arizona are in a dry, desert-like climate zone, while Illinois and Wisconsin share a hot and humid climate zone. In turn, seasons in these different climate zones repeat similar weather patterns each year.

Aside from temperature and humidity, other environmental factors that influence climate zones include latitude, longitude, elevation, precipitation, and cloud cover. Oceans and fog can also play large roles in shaping the weather different climate regions.

Considerations for Different Growth Phases

cannabis seedling covered in condensationHumidity is one of the most important factors to consider for indoor growing.

To find the perfect environmental equilibrium in your growroom, you must consider your climate region as well as the humidity requirements of different cannabis growth phases. Cannabis plants grow the best within the following humidity thresholds:

→ Seedlings: 70-80 percent humidity
Vegetative: 50-70 percent humidity
Flowering: 40-50 percent humidity

Following these figures as a guide, you can figure out your equipment needs for regulating the humidity in your indoor garden.


Humidifiers & Dehumidifiers

Since seedlings and cannabis plants in vegetative growth require high humidity, people growing in dry climates should consider using humidifiers. The Cloudforge Series from AC Infinity is designed with smart controls and precision vapors to obtain the optimal humidity. This high-quality humidifier includes a 4.5L water tank and an extendable tube that can reach more than 4 feet in length — making it the perfect choice for small spaces like grow tents.

If your garden is located in a more humid region like the Pacific Northwest, you should consider adding a dehumidifier to your flowering room. When it rains regularly outdoors, it can be difficult to keep humidity levels below 50 percent — even with a powerful exhaust system or AC unit. In turn, consistent high humidity levels in your flowering room can lead to a devastating botrytis outbreak.



Different Climate Regions in the United States

The United States has several unique climate regions shaped by mountains, oceans, latitude, longitude, and precipitation.

satellite image of north americaNo matter where you live, the outdoor climate will affect the ambient conditions of your indoor garden.

High Plains

The High Plains encompass the region between the Mountain West and the Midwest — including states like Nebraska, South Dakota, and Kansas. The eastern side of mountainous states like Colorado, Wyoming, and Montana also lie within the High Plains.

The High Plains is a dry region that receives 10-20 inches of rain per year. Since the region is located far north, the High Plains experience all four seasons and get quite cold in the winter. Average high temps are around 50°F while the average lows are near 30°F.

Since it is a dry climate that doesn’t get too hot, the High Plains offer great weather for indoor cannabis growing.


Northwest Coastal

Featuring states like Idaho, Oregon, and Washington, the Northwest Coastal region is one of the rainiest zones in the country.

Depending on the location in question, this region averages anywhere from 60 to 240 inches of rain.

Since this area is bordered by the Pacific Ocean, it has a more mild and more temperate climate than other regions at similar latitudes. Average high temperatures range anywhere from 60-70°F, while low temps are around 40°F. It rarely freezes in the Northwest Coastal region.

Indoor growers in the Northwest Coast region often take extra steps to remove excess humidity from flowering rooms.

Midwest & Mid-Atlantic

The Midwest & Mid-Atlantic regions occupy Illinois, Michigan, Pennsylvania, and New England. States in this region average around 30 inches of rain per year.

The Midwest & Mid-Atlantic zone features dramatic shifts from season-to-season. It is known for hot and humid summers, with average high temps around 75°F. The area has cold, snowy winters with lower humidity levels.

Indoor growers in the Midwest & Mid-Atlantic often must make alterations to their operations as the seasons change — such as adding AC in the summertime.

South & Southeast

The climate in the South and Southeast is hot and humid in the summer and mild in the winter. Among others, states in this region include North Carolina, Tennessee, Florida, and Georgia.

With subtropical weather coming from the Gulf of Mexico, the South and Southeast get more than 60 inches of rain each year. Average high temperatures in the South and Southeast are near 90°F and low temps around 45°F.

Due to the hot and humid conditions of the South and Southeast, growers in this region often go to great lengths to keep their rooms at optimal levels.


With a desert climate, the Southwest is the driest region in the United States. It encompasses states like California, Arizona, Utah, and New Mexico. High temperatures in the lower elevations of the Southwest average around 100°F, with lows near 50°F.

While relatively dry, precipitation levels in the Southwest range anywhere from five to 14 inches per year. Rainfall patterns in the area are dictated by monsoon flows from the Gulf of California.

Indoor growers in the southwest must work hard to combat the heat for six to nine months out of the year. Many also choose to supplement their clone and veg rooms with additional humidity.

Since outdoor weather will always impact indoor conditions, accounting for humidity levels in your climate region is crucial for maximizing output. By studying your climate zone, you can get the right equipment to regulate humidity with precision. In turn, you can use the environment to stimulate prolific development during early stages of growth and reduce the spread of pathogens during flowering.

By using your indoor growing experience as a catalyst for researching weather patterns, you expand your overall knowledge of horticulture. In turn, with an increased awareness of local climate, your indoor growing skills have the potential to boost your outdoor gardening abilities if you see fit. In either case, a strong understanding of local weather will allow you to better make critical decisions related to strain selection, irrigation systems, nutrient regimes, and more.

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AC Infinity is the foremost name in air delivery systems, designing and developing the latest innovations in cooling and ventilation technology. They offer a suite of quiet inline fans that automate the growing progress and track key metrics. Visit or contact [email protected] to learn more.


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Presented By

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Written by Kent Gruetzmacher | Writer, Owner of KCG Content

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Kent Gruetzmacher MFA is a Colorado-based writer and owner of the writing and marketing firm KCG Content. Kent has been working in the cannabis and hydroponics space for over a decade. Beginning in California in 2009, he has held positions in cultivation, operations, marketing, and business development. Looking specifically to writing, Kent has worked with many of the leading publications and marketing agencies in the cannabis space. His writing has been recognized by such icons as Steve D’Angelo and Rick Simpson.

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