diff --git a/index.html b/index.html
index d420ccf..68b5639 100644
--- a/index.html
+++ b/index.html
@@ -485,7 +485,7 @@
Okay, this isn't an "intervention" we can control, but it will help! Some news outlets report that summer won't do anything to COVID-19. They're half right: summer won't get R < 1, but it will reduce R.
- For COVID-19, every extra 1° Celsius (2.2° Fahrenheit) makes R drop by 1.2%.35 The summer-winter difference in New York City is 15°C (60°F), so summer will make R drop by 18%.
+ For COVID-19, every extra 1° Celsius (1.8° Fahrenheit) makes R drop by 1.2%.35 The summer-winter difference in New York City is 15°C (27°F), so summer will make R drop by 18%.
diff --git a/words/words.html b/words/words.html
index 396aa37..807cdef 100644
--- a/words/words.html
+++ b/words/words.html
@@ -435,7 +435,7 @@ the
second-most important idea in Epidemiology 101:
Okay, this isn't an "intervention" we can control, but it will help! Some news outlets report that summer won't do anything to COVID-19. They're half right: summer won't get R < 1, but it will reduce R.
-
For COVID-19, every extra 1° Celsius (2.2° Fahrenheit) makes R drop by 1.2%.35 The summer-winter difference in New York City is 15°C (60°F), so summer will make R drop by 18%.
+
For COVID-19, every extra 1° Celsius (1.8° Fahrenheit) makes R drop by 1.2%.35 The summer-winter difference in New York City is 15°C (27°F), so summer will make R drop by 18%.
diff --git a/words/words.md b/words/words.md
index 691356b..8c86858 100644
--- a/words/words.md
+++ b/words/words.md
@@ -524,7 +524,7 @@ Masks *alone* won't get R < 1. But if handwashing & "Test, Trace, Isolate" only
Okay, this isn't an "intervention" we can control, but it will help! Some news outlets report that summer won't do anything to COVID-19. They're half right: summer won't get R < 1, but it *will* reduce R.
-For COVID-19, every extra 1° Celsius (2.2° Fahrenheit) makes R drop by 1.2%.[^heat] The summer-winter difference in New York City is 15°C (60°F), so summer will make R drop by 18%.
+For COVID-19, every extra 1° Celsius (1.8° Fahrenheit) makes R drop by 1.2%.[^heat] The summer-winter difference in New York City is 15°C (27°F), so summer will make R drop by 18%.
[^heat]: “One-degree Celsius increase in temperature [...] lower[s] R by 0.0225” and “The average R-value of these 100 cities is 1.83”. 0.0225 ÷ 1.83 = ~1.2%. [Wang, Jingyuan and Tang, Ke and Feng, Kai and Lv, Weifeng](https://papers.ssrn.com/sol3/Papers.cfm?abstract_id=3551767)