How Long Can Oatmeal Sit Out?

Oatmeal is a proper breakfast food that is eaten throughout the world. It is prepared from oat grains and comes in many different forms including white oats, steel-cut oats, and rolled oats. Normally, it is prepared using milk or water and something to sweeten it.

If you decide to cook steel-cut oats instead of rolled oats, it can be a time-consuming process. Because of this, some people prefer to prep their oats ahead of time and leave them sitting out until they are ready to eat them. 

The general rule is that cooked oatmeal can sit out at room temperature for up to two hours. Anything past two hours is when bacteria growth will begin to skyrocket which could result in food poisoning if you consume it.

However, the exact length of time that oatmeal can be left out will depend on how it was prepared and what ingredients it includes.

Different Rules for Leaving Oatmeal Out

There are several different rules for leaving oatmeal out. These rules depend on whether or not the oats have been cooked, how they’re stored, the added ingredients, and the temperature at which they’re left out.

Cooked Oatmeal

It is recommended that you leave cooked oatmeal at room temperature for no more than two hours. After any perishable, wet food is left at room temperature for more than two hours it will reach the “danger zone.”

The “danger zone” is temperatures between 40 and 140 degrees Fahrenheit. This is the temperature at which rapid bacterial growth can occur. Once you have left your cooked oatmeal out for more than two hours, the bacteria levels will skyrocket and the oatmeal should be thrown away.

Related Posts  How Long Can Tuna Sit Out Unrefrigerated?

Dry Oats

There are two types of dry oats, processed and unprocessed, and each has its own shelf life when at room temperature.

Oats that have been commercially processed and stabilized can be kept in an airtight container at room temperature for up to twelve months. 

Unstabilized oats have a far shorter shelf life and will only last 3-4 months at room temperature before they should be thrown out.

Instant Oatmeal

Instant oatmeal is a bit different from regular, processed oatmeal because it contains other ingredients to flavor the oats.

Instant oatmeal containing dried fruits or milk typically has a shorter shelf life than regular oatmeal. However, the exact shelf life will vary based on the brand and how the other ingredients in the oatmeal have been stabilized. The best way to know how long your instant oatmeal will last is by checking for the expiration date on the package.

How Long Can Oatmeal With Water Sit Out?

Oatmeal that has been prepared with water can sit out at room temperature for roughly two hours before you should throw it away. After two hours, bacteria growth will increase. For this reason, cooked oatmeal should always be refrigerated if it will not be consumed immediately.

How Long Can Oatmeal With Milk Sit Out?

Oatmeal made with milk can sit out for approximately two hours after which it should be thrown away. This is an especially important rule to follow when dealing with oatmeal that has been prepared with milk.

Dairy products, more so than grain products, can rapidly spoil when left at room temperature. This is why you will notice that almost all dairy products unless they are highly processed, must be refrigerated. If not, they will go bad which can cause severe foodborne illnesses. 

How To Tell If Oatmeal Is Bad?

There are three very easy ways to tell if oatmeal has gone bad, the smell and the presence of mold or insects. 

Related Posts  How Long Do Onions Last? A Guide to Onion Shelf Life

Simply open your container of oatmeal up and take a sniff. If the oatmeal has a pungent, acrid scent then it has gone bad and should be thrown away.

If the oatmeal is cooked, something you can check for is the presence of mold. If the oatmeal has fluffy patches of gray, white, or black mold growing on it, the oatmeal has gone bad and should be thrown away. 

If the oatmeal is dry, an easy way to tell if your oatmeal is still safe to eat is by checking for live or dead insects. If insects have made their way into the oatmeal, it is likely no longer safe to eat and should be tossed. Alternatively, if the oatmeal is fairly new, you can freeze the oatmeal to kill the insects and then pick the dead insects out. 

Can You Freeze Oatmeal?

Yes, you can freeze both fresh and dry oatmeal to give it a longer shelf life. However, the process of freezing fresh and dry oatmeal is different and will require slightly different supplies.

Freezing Dry Oatmeal

Freezing dry oatmeal is an extremely easy process. All you’ll need to do is pour your dry oatmeal into a large freezer bag and squeeze as much of the air out as possible. You can add a second freezer bag or place the bag in an airtight container for extra protection. 

Just toss the bag in the freezer and keep it frozen until you are ready to cook it. Thawing time is extremely minimal since there is very little moisture in dry oatmeal.

Freezing Cooked Oatmeal

To freeze cooked oatmeal you will first need to prepare a batch of oatmeal and let it cool to room temperature. Then place it in the fridge for another few hours to chill further. This will make the freezing time shorter and help the oatmeal to freeze evenly.

Next, you will want to separate your cooked oatmeal into individual portions. This will speed up both freezing and thawing time and make it easier for you to only thaw as much as you want to eat. A good way to do this is by freezing your portions of oatmeal in a muffin tin. That way you can just pop out a few tins of oatmeal and heat that up for breakfast.

Related Posts  Do Corn Tortillas Need to be Refrigerated? Here's What You Need to Know

Once the oatmeal has been separated into portions you’ll want to wrap it tightly with plastic wrap. This will help to prevent freezer burn and keep the oatmeal from drying out while it’s in the fridge. 

After the oatmeal has been plastic wrapped you will want to place it in a freezer bag making sure to squeeze out as much air as possible. This step provides an extra layer of protection against freezer burn and drying out. After it’s all wrapped up you can toss it in the freezer where it will stay fresh for several months.

Once you are ready to thaw your oatmeal you should place it in the fridge the night before. This will let it thaw out gradually and keep the oatmeal out of the danger zone. After the oatmeal is fully thawed you can go ahead and reheat the oatmeal.

Related post: How Long Can Soy Milk Sit Out


When you are preparing oatmeal you may not end up eating it all. Then you are left deciding whether to leave it on the counter or pack it away and put it in the fridge or freezer.

Cooked oatmeal should be left at room temperature for a maximum of two hours. After two hours, rapid bacterial growth will occur which can make you sick. The best way to store cooked oatmeal is in an airtight container in the fridge or freezer. 

The low temperatures will help to keep the oatmeal from spoiling and maintain its flavor and texture.