I want to get an estimate on how cold my pond will get.

It is a 1 acre pond in Central Florida USA. It has an average depth of 4 feet. There is not much circulation in the pond. It gets direct sunlight during these cold months.

These are the average temperatures (high + low)/2 in Farenheit.

              °F       °C
November      65      18.3 
December      60      15.6
January       57.5    14.2
February      60      15.6
March         65.5    18.6

What is the warmest temperature the water will remain? Its not as simple as looking at the numbers and will take some judgement. The top half of the water will certainly be warmer than the bottom, and the 1 foot shallows near the bank will be even warmer due to the direct sun.

The fish I am considering putting into this pond will have normal feeding behaviors recommended at 68 degrees but I estimate that it will go into conservation mode and not eat at around 60 degrees or possibly die.

Is it likely that the fish will be able to find water at or above 68 degrees during these months (on the bank or near the surface for the greater part of the day?)

I don't have tools to measure the temperature of different parts of the water, and with the large amount of rain we have had lately the temp would be off.

Thank you for any insight.

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    $\begingroup$ Don't be fooled by averages. The average family has two and a half kids, but I've never seen a family with two and a half kids. Stock your pond with hardy, temperate climate fish, there are plenty of them, then you won't have to worry. The important thing is to make sure your pond is well oxygenated. $\endgroup$ Sep 4 '19 at 16:02
  • $\begingroup$ if you update your question with what types of fish you want to keep in your pond i might be able to give you some advice and improve my answer below.or you can post a new question over at pets.stackexchange.com $\endgroup$ Sep 5 '19 at 8:39
  • $\begingroup$ Averages aren't worth much. My averages are Dec =52 F, Jan = 50.5 F , Feb = 54.5 F , but in any of those months we get a few days of about 20 F( 24 hr average). Record breaking lows also occur despite global warming. $\endgroup$ Sep 6 '19 at 0:42

I doubt a pond temperature will stay above 60 in central FL winter.Without circulation there will be large temperature gradients caused by stratification, especially on warm days. Surface plants probably lower the maximum temperatures. For such a large pond ,the relative humidity and wind will make a temperature difference ( evaporation is a major heat loss). As a comparison , I have a small ( 1000 gal) pond with circulation and although our air temperatures are usually 98 -day and 76-night, I have never measured a temperature over 83 F and usually lower. So the water temperature is definitely lower than the average air temperature in summer. In winter I protect my pond from low temperatures but it gets to 52 F . However, tropical fish like danios, swordtails and mollies survive that temperature in pond conditions , although books will say such temperature will kill them . What fish do you plan to have ? With the history that FL has for raising tropical fish , I would think there would be information available , such as from the FL Dept of Agriculture.


Your fish will be fine even in the coldest months of the year,And they will not stop eating if the temparature gets lower but their digestion of the food do slow down at the low temparatures.

In the coldest part ot the year the temparature at the bottom of a one and a half metres deep pond will stay at or close to the average temparature in your area,and the surface water will get a significantly higher temparature during the day and evening.

If you take a look at the native area of your fish you will find the type of climate they are adapted to(look at the day/night temparature)The fish can often live well outside of this temparature range.

Sorry for not answering what temparature you will have in your pond,there is a lot of things that can change the temparature in a small body of water.

If the water in your pond are at 20C and you replace half of this with 10C rainwater you will only change the temparature by 5C(not totaly correct but close,it is for water that is fully mixed and not for the temparature layers you might see in a pond).

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    $\begingroup$ Note that replacing half the water in this pond would require 24" of rain. $\endgroup$ Sep 6 '19 at 0:45

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