Does maple sap flow immediately after a hard freeze?

It was C-O-L-D the last two days. The temperature was in the single digits. On Monday, it went down to 6 degrees. On Tuesday, the high was 30. Today, the temperature got up to 44 at 9 pm with the temperature still rising.

My hope was that today would be a great day for sap.

weather in the 40s

I thought that with the freezing temperatures overnight and the temperature in the 40s today that we had the perfect conditions for sap.

Turns out, I was wrong. Got home from work, checked my lines. No running sap. No sap in the buckets.


When I decided to get started this past weekend, I was counting on today to be a good day.

Update 2/2/2019

Just thought I’d add to this thread, about 10 days later. We had a serious cold-snap here. They were calling it an arctic vortex, which pushed really cold air down from…the artic…I suppose.

Temperatures got down to negative digits, which is rare where I live.

However, the forecast looks great, from today forward. The temperature got up to 32 yesterday and is currently 39 degrees at noon–the temperature rose about 20 degrees in 3 hours.

So factor that into your own predictions.

Does sap flow immediately after a hard freeze?

The sap is supposed to flow best after a light freeze when the temperature reaches the low 40s.

This temperature differential creates pressure that causes the sap to run.

However, after a hard freeze, like today, the sap was not flowing, even though the temperature was in the 40s.


Seems like the sap is still frozen, either literally, or figuratively.

The temperature will continue to rise throughout the night and until tomorrow at around 1 pm before it starts to tail off into the evening.

The other big question I was trying to answer this year is–when is the best time to tap a maple tree in Southeastern PA?

Answer: not yet.

Hoping to see a better outcome tomorrow.

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