Why Is My Cart Foggy? Temperature, Storage, and Clear Oil Tips

Published on Dec 03, 2025 • Reviewed & Updated on Dec 03, 2025 by Lindsey Goldstein

Quick Answer: A foggy vape cart happens when the oil gets cold and cannabinoids crystallize or separate. To fix it, gently warm the cart in your hand or pocket for a few minutes. If the oil doesn’t clear after warming, the cart may be old, oxidized, poorly stored, or made with low-quality distillate.

If you've ever pulled out a vape cart and noticed the oil looks milky, hazy, or foggy instead of clear amber, you're not the only one. Cloudy carts are one of the most common questions we hear from users who worry their product is contaminated or expired.

In most cases, a foggy cart is simply cold. Cannabis oil contains cannabinoids and terpenes that crystallize or separate when temperatures drop, creating a cloudy appearance that clears up with gentle warming. This guide explains why carts turn foggy, how to fix cloudiness fast, and when to replace a cart that won't clear.

Key Takeaways

Foggy carts occur when cannabinoids crystallize from cold temperatures, storage mistakes, oxidation, or low-quality distillate, and most carts clear with gentle warming.
Carts turn cloudy below about 60°F because cannabinoids fall out of solution and terpenes separate, especially in oils rich in THCp or THCa.
Shipping, winter storage, and temperature swings are leading causes of cloudiness, while oxidation and impurities create fogginess that warming cannot fix.
Cloudiness that does not clear after warming may signal contamination, lipids, waxes, or degraded cannabinoids, making replacement the safest option.
For consistently clear, lab-tested cartridges formulated for stability, see the full collection from Mellow Fellow.

What Makes a Cart Look Cloudy or Foggy?

Cloudy or foggy vape carts usually come down to temperature. Cannabis oil is a blend of cannabinoids and terpenes that stay clear only when fully dissolved. When the oil drops below about 60°F, cannabinoids can fall out of solution, forming tiny crystals or creating a milky haze inside the cartridge. Terpenes can also separate when the oil cools, causing droplets or a thin cloudy layer near the top.

Cold storage, temperature swings during shipping, or leaving a cart in a car overnight are the most common triggers. THCa, THCp, and some minor cannabinoids crystallize faster than Delta 9 THC, so carts rich in those compounds cloud up more easily.

Thick oil alone is not a problem. Slow-moving, viscous oil is normal, while true cloudiness indicates phase separation or crystallization. If the cart still looks translucent amber when held to the light, it is probably just cold. If it turns opaque, white, or shows floating particles, it is worth inspecting more closely. Proper storage helps prevent these changes and keeps the oil stable.

Common Causes of Foggy or Cloudy Carts

There are several reasons why carts get foggy or cloudy, including cold exposure, the type of cannabinoid, poor-quality distillate, and age.

Cold Exposure

Most cannabis oil stays liquid and clear between 68°F and 80°F. Below 60°F, cannabinoids may begin to solidify. If you store carts in a basement, garage, or unheated room during winter, expect cloudiness. Shipping during cold months also triggers crystallization, especially for carts that sit in trucks or mailboxes for hours.

Cannabinoid Type and Concentration

High-potency carts with THCp, THCa, or blended cannabinoids fog up faster than standard Delta 9 distillate. These compounds have higher melting points and form crystals more readily.

Live resin carts, which contain more terpenes and minor cannabinoids, can also show cloudiness when terpene fractions separate from the heavier cannabinoid oil. If you're curious about what live resin actually is, the extraction process preserves more of these temperature-sensitive compounds.

Poor-Quality Distillate

Low-grade distillate often contains residual fats, lipids, or plant waxes that weren't filtered out during extraction. These impurities make the oil cloudy at any temperature.

If warming doesn't clear the fog, the distillate may be cut with low-quality additives or contaminated with residual solvents. Always check lab results and buy from brands that publish certificates of analysis (COAs) for every batch.

Age and Oxidation

Over time, cannabinoids degrade and oxidize, especially when exposed to light or air. Oxidized oil turns darker and may develop a hazy appearance. If your cart is more than six months old or has been opened and stored improperly, oxidation could be the cause. Properly sealed, stored carts should stay clear for up to a year.

Improper Storage

Storing carts on their side or upside down can cause oil to leak into the airflow chamber, where it cools and thickens. This creates a cloudy ring or buildup near the mouthpiece. Always store carts upright in a cool, dark place to prevent leaks and maintain oil clarity. Understanding how long carts last helps you plan storage and rotation.

How to Fix a Foggy Cart Fast

Warm the cart slowly. Hold it in your closed hand for 5-10 minutes, or place it in a shirt pocket. Body heat is enough to dissolve crystals and restore clarity. Avoid using hair dryers, microwaves, or hot water, as rapid heating can damage the coil, degrade cannabinoids, or crack the cartridge housing.

If hand-warming doesn't work, try setting the cart upright in a room-temperature area for 20-30 minutes. Some high-THCp or THCa carts need longer to fully clear. Gentle heat from a warm room (around 72°F) is safer than direct heat sources.

Once the oil clears, test the cart with a short pull. If vapor production is normal and flavor is clean, the cart is fine. If the vapor tastes harsh, burnt, or off, the oil may have degraded or the coil may have been damaged by repeated freeze-thaw cycles.

For troubleshooting other common cart issues, see how to fix a burnt weed vape cart for coil care and device settings.

Cloudiness vs. Contamination: When to Worry

Not all cloudy oil is safe to use. Here's how to tell the difference between reversible crystallization and real contamination.

Sign	Likely Cause	Action
Clears after warming	Cold-induced crystallization	Safe to use; store warmer
Stays cloudy after 30 min at room temp	Low-quality distillate or contamination	Replace cart; check COA
White or opaque particles	Lipid or wax residue	Do not use; contact vendor
Dark, hazy, and thick	Oxidation or expired oil	Replace cart
Oil leaks or pools in airflow	Storage damage or overfilling	Wipe clean; use upright only

If the cart came from a reputable brand with published lab results and the oil clears when warmed, you're good.

If it stays foggy or you see floating debris, reach out to the vendor for a replacement. Mellow Fellow's third-party testing ensures clean distillate and consistent clarity across all cartridge formats.

Prevent Fogging with Better Storage

Here’s how to prevent foggy carts with proper storage.

Store carts upright in a drawer or case at stable room temperature.
Avoid windowsills, car glove boxes, or any spot with direct sunlight or temperature swings.
If you live in a cold climate, keep carts in a bedroom or office where heat runs regularly.
Use airtight containers or ziplock bags to minimize air exposure, which accelerates oxidation.
For long-term storage, a small hard-shell case works well to protect carts from light and physical damage.
Label carts with purchase dates so you can track age and rotate stock.

Before using a cart that's been stored for weeks, let it sit at room temperature for 15-20 minutes and inspect the oil under light. Clear, amber oil with no haze or separation means the cart is ready. If you see cloudiness, warm it gently before your first pull.

Why Some Carts Fog More Than Others

Live resin and terp sauce cartridges contain higher terpene concentrations, which separate more easily than pure distillate. Terpenes are lighter and less viscous than cannabinoids, so they can form a hazy layer or small bubbles near the top of the reservoir. This is normal and clears with a gentle shake or warming.

Single-cannabinoid carts like pure Delta 8 or Delta 9 distillate tend to stay clearer because they lack the complex terpene profiles that cause separation. Blended carts with THCp, HHC, or minor cannabinoids may fog more often due to the variety of melting points and solubility differences between compounds.

Understanding how live resin differs from distillate helps explain why some carts fog more than others.

Some manufacturers add viscosity modifiers or cutting agents to keep oil flowing at lower temperatures. While these additives can reduce fogging, they may dilute potency or affect flavor. Mellow Fellow's formulations balance clarity, flavor, and effect without unnecessary fillers, relying on refined distillate and natural terpenes to maintain consistency.

Mellow Fellow Cartridges Built for Clarity and Consistency

Mellow Fellow's vape cartridges are designed with refined distillate, natural terpenes, and precise cannabinoid ratios that resist crystallization and maintain clarity across normal storage conditions. Each batch is third-party tested for purity, potency, and contaminants, with full lab results available through QR codes on every package.

Motivation Blend - Terp Sauce 2ml Vape Cartridge - Kali Mist (Sativa)

This sativa-leaning terp sauce cart combines THCv, H4CBD, and CBG for focus and energy without jitters. The Kali Mist profile delivers bright citrus and pine notes that stay crisp across the full reservoir. Terp sauce formulations may show light haze when cold but clear quickly with hand-warming.

Dream Blend 1ml Live Resin Vape Cartridge - Northern Lights (Indica)

Live resin preserves full-spectrum terpenes and cannabinoids for deeper flavor and balanced effects. Northern Lights offers earthy, sweet, and slightly spicy notes that suit evening use. Live resin carts may develop minor cloudiness in cold storage but restore clarity at room temperature within 10 minutes.

THCp 0.5ml Vape Cartridge - TKO (Hybrid)

High-potency THCp carts deliver strong effects in smaller servings. TKO's hybrid profile balances body relaxation with mental clarity, making it useful for experienced users who want precise dosing. THCp crystallizes faster than Delta 9, so store this cart at stable room temp and warm before use if it fogs.

Sour Diesel (Sativa) Delta 8 1ml Vape Cartridge

Delta 8 offers milder psychoactive effects and smoother pulls for new or returning users. Sour Diesel's sharp, fuel-forward terpene profile pairs well with daytime activities. Delta 8 distillate resists crystallization better than THCp or THCa, so this cart stays clear longer in variable storage conditions.

Purple Punch (Indica) HHC 1ml Vape Cartridge

HHC provides a unique cannabinoid experience with effects between Delta 8 and Delta 9. Purple Punch brings sweet berry and grape flavors that land smooth on the inhale. HHC distillate holds clarity well, though cold exposure can still cause light fogging that resolves with gentle warming.

Need help choosing the right cart for your device and preferences? Browse Mellow Fellow's full vape cartridge collection for detailed cannabinoid breakdowns, terpene profiles, and batch-specific lab results.

When to Replace a Cloudy Cart

If warming doesn't restore clarity after 30 minutes, or if the oil smells off, tastes burnt, or produces harsh vapor, stop using the cart.

Contaminated or degraded oil can irritate your lungs and won't deliver the intended effects. Contact the vendor with your order details and photos of the cart to request a replacement.

Reputable brands like Mellow Fellow stand behind product quality and will replace defective or damaged carts when storage or shipping issues cause legitimate problems. Always check the expiration date and inspect the cart before use, especially if it's been stored for more than a few months.

Final Thoughts on Cloudy Carts

Foggy vape carts can look alarming, but most cloudiness comes from simple temperature changes. Cold conditions cause cannabinoids and terpenes to separate or crystallize, and gentle warming is usually all it takes to restore clarity.

Proper storage, upright positioning, stable temperatures, and checking lab results help keep carts clear and consistent. Different types of oil, such as live resin, terp sauce, THCp, and Delta 8, also behave differently when cold.

Ready to upgrade to lab-tested cartridges with reliable clarity and consistent effects? Browse Mellow Fellow's live resin disposables for full-spectrum flavor and smooth performance, or check out the store locator to find carts in stock near you.

Frequently Asked Questions

Why Is My Cart Cloudy After I Left It in My Car?

Cold temperatures cause cannabinoids to crystallize and separate from terpenes, creating a cloudy or milky appearance. Warm the cart gently in your hand for 5-10 minutes, and the oil should clear. Avoid leaving carts in cars during winter or storing them in unheated spaces.

Is Cloudy THC Oil Safe to Use?

If the cloudiness clears with gentle warming and the cart was purchased from a reputable brand with lab testing, it's safe to use. If the oil stays cloudy after 30 minutes at room temperature, has floating particles, or smells off, do not use it and contact the vendor for a replacement.

Why Does My Vape Cart Look Foggy Even at Room Temperature?

Persistent fogging at room temperature usually means low-quality distillate with residual fats, lipids, or contaminants that weren't filtered during extraction. Check the brand's lab results and COA. If no testing is available or the oil doesn't clear, replace the cart.

Can I Use a Hair Dryer to Clear a Foggy Cart?

Avoid using hair dryers, microwaves, or hot water. Rapid or uneven heating can damage the coil, crack the cartridge housing, or degrade cannabinoids and terpenes. Hand-warming or placing the cart in a room-temperature area for 15-20 minutes is safer and more effective.

Why Is My Cart Fogging up After I Store It Upright?

If you're storing the cart correctly but it still fogs, the issue is likely temperature-related. Even upright storage in a cold room or near an air vent can cause crystallization. Move the cart to a warmer, stable location away from drafts or temperature swings.

Do Live Resin Carts Fog More Than Distillate Carts?

Yes, live resin and terp sauce carts contain higher terpene concentrations that separate more easily when cold. This creates a hazy layer or light cloudiness that clears with warming. Distillate carts with fewer terpenes tend to stay clearer in variable temperatures.

How Can I Tell if My Cart Is Contaminated vs. Just Cold?

Warm the cart for 10-15 minutes. If it clears and the oil returns to translucent amber, it was just cold. If it stays cloudy, has white particles, or produces harsh vapor, it may be contaminated or expired. Always buy from brands that publish third-party lab results.