Adjusting last frost date for warmer conditions

ABlindHog · January 9, 2016

I am in zone 8a and for the last several years based on all the information I could find I have used March 25th as my average last frost date. It occurred to me that we have been hearing about warming climate conditions for for the last ten years or so and I wondered if my last frost date had changed. I looked in several places and March 25th was still about the average answer. I decided to try to calculate it for myself. Weather underground has a station less than 5 miles from my place and has daily records going back several years. I used the last 10 years with a temperature of 32 degrees or less and got an average date of March 18. That is a full week earlier than conventionally is quoted and as much as 3 weeks earlier than than the latest of those quotes. I calculated again for the last 5 years and got an average last frost date of March 11th.
This may indicate a trend or it may be a result of small sample size there is just no way to be sure. Either way what we are being told about last frost dates may be incorrect.
Has anyone else found this to be the case?

January 9, 2016	#1
ABlindHog Tomatovillian™ Join Date: May 2014 Location: The Texas Hill Country Posts: 149	Adjusting last frost date for warmer conditions I am in zone 8a and for the last several years based on all the information I could find I have used March 25th as my average last frost date. It occurred to me that we have been hearing about warming climate conditions for for the last ten years or so and I wondered if my last frost date had changed. I looked in several places and March 25th was still about the average answer. I decided to try to calculate it for myself. Weather underground has a station less than 5 miles from my place and has daily records going back several years. I used the last 10 years with a temperature of 32 degrees or less and got an average date of March 18. That is a full week earlier than conventionally is quoted and as much as 3 weeks earlier than than the latest of those quotes. I calculated again for the last 5 years and got an average last frost date of March 11th. This may indicate a trend or it may be a result of small sample size there is just no way to be sure. Either way what we are being told about last frost dates may be incorrect. Has anyone else found this to be the case?