diff --git a/examples/weather.cpp b/examples/weather.cpp
index 18b9de1e..24030e33 100644
--- a/examples/weather.cpp
+++ b/examples/weather.cpp
@@ -73,8 +73,8 @@ struct weather_app
 	const float heating = 323.f * (std::exp(cooling * dt) - 1.f) / dt;
 	const float water_heating_factor = 0.9f;
 	const float coriolis = 0.001f;
-	const float coriolis_bands = 6.f;
-	const float band_force = 0.00001f;
+	const float coriolis_bands = 24.f;
+	const float band_force = 0.00004f;
 	const float friction = 0.f;
 	const float slope_friction = 1.f;
 	const float slope_force = 0.001f;
@@ -287,6 +287,9 @@ struct weather_app
 		// Velocity & temperature advection
 		for (int i = 0; i < N; ++i)
 		{
+			new_velocity_(i, 0) = velocity_(i, 0);
+			new_velocity_(i, N - 1) = velocity_(i,  N - 1);
+
 			new_temperature_(i, 0) = temperature_(i, 0);
 			new_temperature_(i, N - 1) = temperature_(i,  N - 1);
 
@@ -295,6 +298,9 @@ struct weather_app
 
 			if (!periodic_x)
 			{
+				new_velocity_(0, i) = velocity_(0, i);
+				new_velocity_(N - 1, i) = velocity_(N - 1, i);
+
 				new_temperature_(0, i) = temperature_(0, i);
 				new_temperature_(N - 1, i) = temperature_(N - 1, i);
 
@@ -316,7 +322,7 @@ struct weather_app
 					p[0] = math::clamp(p[0], {0.f, N - 1.f});
 
 				int ix = std::floor(p[0]);
-				int iy = std::min<int>(N - 1, std::floor(p[1]));
+				int iy = std::min<int>(N - 2, std::floor(p[1]));
 
 				if (!periodic_x)
 					ix = std::min(N - 1, ix);
@@ -348,9 +354,7 @@ struct weather_app
 		std::swap(humidity_, new_humidity_);
 
 		// Apply velocity diffusion
-		for (int y = 0; y < N; ++y)
-			for (int x = 0; x < N; ++x)
-				new_velocity_(x, y) = velocity_(x, y);
+		std::copy(velocity_.begin(), velocity_.end(), new_velocity_.begin());
 		for (int y = 1; y < N - 1; ++y)
 		{
 			for (int x = xmin; x < xmax; ++x)
@@ -402,13 +406,13 @@ struct weather_app
 
 				[[maybe_unused]] math::vector terrain_gradient
 				{
-					(std::max(0.f, terrain_(x + 1, y)) - std::max(0.f, terrain_(x - 1, y))) / 2.f,
-					(std::max(0.f, terrain_(x, y + 1)) - std::max(0.f, terrain_(x, y - 1))) / 2.f,
+					(std::max(0.f, terrain_(wrap(x + 1), y)) - std::max(0.f, terrain_(wrap(x - 1), y))) / 2.f,
+					(std::max(0.f, terrain_(wrap(x), y + 1)) - std::max(0.f, terrain_(wrap(x), y - 1))) / 2.f,
 				};
 
 				[[maybe_unused]] math::vector temperature_gradient
 				{
-					(temperature_(x + 1, y) - temperature_(x - 1, y)) / 2.f,
+					(temperature_(wrap(x + 1), y) - temperature_(wrap(x - 1), y)) / 2.f,
 					(temperature_(x, y + 1) - temperature_(x, y - 1)) / 2.f,
 				};
 
@@ -746,7 +750,7 @@ struct weather_app
 				{
 					// color = gfx::blend(color, map_color(precipitation_(x, y), {1.f, 1.f, 1.f, -1.f}, {1.f, 1.f, 1.f, 1.f}));
 
-					float alpha = 2.f / (1.f + std::exp(- 0.1f * precipitation_(x, y))) - 1.f;
+					float alpha = 2.f / (1.f + std::exp(- 0.5f * precipitation_(x, y))) - 1.f;
 
 					gfx::color_4f cloud_color{1.f, 1.f, 1.f, alpha * 0.875f};