Before You Go!
Enter your email and receive a link to our free Buyer’s Guide
What Temperature Should You Keep Your Hot Tub at When You're Not Using It?
The Quick Answer
If you’ll soak again within a few days, leave your hot tub at your normal soaking temperature. If it will sit unused for a week or more, lower it about 5°F and warm it back up before you return. In Redding’s colder months, keep it at 90°F or higher, and never above 104°F.
That is the short version from the Affordable Hot Tubs team in Redding, CA. The right number depends on how long the spa will sit, what the weather is doing, and whether you can adjust it from your phone. The table below covers each situation.
Hot Tub Temperature When Not in Use, by Situation
Match your setting to how long the spa will sit and who is watching it.
| How long it sits unused | Recommended setting | Why |
|---|---|---|
| 1–3 days | Your normal soaking temperature (100–104°F) | Not worth the recovery time to lower it |
| 4–7 days, you’re home | Lower about 5°F | Trims energy use while staying well clear of freezing risk |
| 1–2 weeks, you’re traveling | Lower about 5°F; check it daily from an app or have a friend check it | Short trips don’t require winterizing if someone is monitoring |
| Rarely used all winter, not winterized | 90°F or higher during freezing weather | Gives a buffer against frozen plumbing on cold Redding nights |
| Absolute floor for a low-use spa | 80°F | Caldera Spas’ published minimum for spas that won’t be used much |
| Gone for the whole season | Winterize per your owner’s manual | Drain the spa, clear the lines and add spa antifreeze instead of heating a spa no one is using |
Never set a hot tub above 104°F. That is the widely accepted safety ceiling for soaking, and it doesn’t change when the spa is idle.
Redding’s Two Problems: Frosty Nights and Triple-Digit Days
Redding owners deal with both ends of the thermometer, so the idle setting shifts with the season.
November through February
Clear winter nights in the north state can dip near or below freezing. Most modern spas have built-in freeze protection. On Caldera’s Utopia and Paradise series, for example, circulation and heating kick on when temperatures fall to about 40°F.
That protection only works if the water can circulate. If evaporation pulls the level below the skimmer, the pump can’t move water and the heater can’t warm it. Cold, dry air speeds evaporation, so top off the water before any stretch away from home.
June through September
In summer, the problem flips. A covered spa sitting in afternoon sun can drift above its setpoint on its own, because the heater can only add warmth, not remove it. Lowering the dial to save energy does little when the air is 105°F.
If you want cooler water for summer soaks, ask about the Caldera CoolZone system, which can actively cool the water. Shade over the spa during the hottest hours also helps.
Lower It While You’re Away, Warm It Before You’re Home
A smart-spa app turns the “lower it or leave it” question into a non-issue. You can drop the temperature when you leave and raise it again from your phone the day before you return.
The Caldera Spas app, powered by the Connected Spa Kit, lets you:
- Check water temperature and key spa functions in real time
- Change settings and lock the spa remotely
- Get alerts when something needs attention
- Add guest users, such as a neighbor, who can also keep an eye on it
Plan the warm-up around your heater’s pace. A 5°F recovery usually takes a couple of hours on a standard 240-volt spa, while a cold start can take most of a day. Your owner’s manual lists your model’s heater size.
Four Things That Matter More Than the Number on the Dial
An idle spa loses most of its heat, and takes most of its risk, through things other than the thermostat.
- Heat escaping through the top. A thermal spa blanket under the cover cuts heat loss and eases the load on the heater. In a winter storm, a weatherproof tarp over the cover adds another layer.
- Jets and blowers running when nobody’s in. Air blowers push cold air through warm water. Keep them off while the spa is idle so the heater isn’t fighting them.
- Exposed plumbing. Foam pipe insulation or heat cable on exposed lines lowers the chance of a freeze crack, even with the water at a safe temperature.
- No backup power plan. If you live where outages run long, a generator or battery backup keeps circulation and freeze protection running.
Before You Leave: A 5-Minute Checklist
☐ Set the temperature for how long you’ll be gone (see the table above)
☐ Top off the water so it sits well above the skimmer
☐ Clean or rinse the filters so circulation stays strong
☐ Turn off air blowers and any jet timers you don’t need
☐ Latch the cover and fasten the tie-downs
☐ Confirm the app shows the spa online, or give a neighbor guest access
☐ Set a phone reminder to warm the spa back up before you return
Frequently Asked Questions
What is the lowest temperature I can set my hot tub to when I’m not using it?
Caldera Spas lists 80°F as the recommended minimum for a spa that won’t be used much. During freezing weather in Redding, we suggest staying at 90°F or higher for a wider safety margin.
How much should I lower my hot tub temperature when I’m away?
About 5°F is the sweet spot for trips of a week or two. It saves some energy without leaving you a long wait to reheat when you get home.
Do I need to winterize my hot tub for a one-week trip?
No. A trip of about a week doesn’t call for winterizing, as long as the spa stays powered and someone checks it, in person or through an app.
Is it OK to leave my hot tub at 104°F when no one is using it?
Yes, 104°F is safe to hold, but there’s no benefit to keeping it there while idle. Never set it higher than 104°F.
Why is my hot tub hotter than the setting in summer?
The heater can only warm water, not cool it. In Redding’s summer heat, sun and air temperature can push water above the setpoint. A cooling system such as Caldera CoolZone or added shade fixes it.
How often should I check my hot tub temperature when it’s not in use?
Once a day in winter, either at the spa or in the app. Daily checks give you time to react if a heater or pump stops working.
Get Help From Affordable Hot Tubs in Redding
Not sure what your spa’s heater can handle, or want remote control before your next trip? Affordable Hot Tubs can add a Connected Spa Kit, fit a new insulated cover, or check your freeze protection before winter.
Visit our showroom at 885 Commerce Street, Redding, CA 96002, call 530-768-1222, or request service online.