diff --git a/R/inst/stan/prophet.stan b/R/inst/stan/prophet.stan
index a2dcfff..922c960 100644
--- a/R/inst/stan/prophet.stan
+++ b/R/inst/stan/prophet.stan
@@ -104,7 +104,7 @@ model {
   k ~ normal(0, 5);
   m ~ normal(0, 5);
   delta ~ double_exponential(0, tau);
-  sigma_obs ~ normal(0, 0.1);
+  sigma_obs ~ normal(0, 0.5);
   beta ~ normal(0, sigmas);
 
   // Likelihood
diff --git a/python/stan/unix/prophet.stan b/python/stan/unix/prophet.stan
index a2dcfff..922c960 100644
--- a/python/stan/unix/prophet.stan
+++ b/python/stan/unix/prophet.stan
@@ -104,7 +104,7 @@ model {
   k ~ normal(0, 5);
   m ~ normal(0, 5);
   delta ~ double_exponential(0, tau);
-  sigma_obs ~ normal(0, 0.1);
+  sigma_obs ~ normal(0, 0.5);
   beta ~ normal(0, sigmas);
 
   // Likelihood
diff --git a/python/stan/win/prophet.stan b/python/stan/win/prophet.stan
index 787c452..83dbf96 100644
--- a/python/stan/win/prophet.stan
+++ b/python/stan/win/prophet.stan
@@ -149,7 +149,7 @@ model {
   k ~ normal(0, 5);
   m ~ normal(0, 5);
   delta ~ double_exponential(0, tau);
-  sigma_obs ~ normal(0, 0.1);
+  sigma_obs ~ normal(0, 0.5);
   beta ~ normal(0, sigmas);
 
   // Likelihood