diff --git a/packages/basemap/setup.py b/packages/basemap/setup.py
index 17cc473f6..da0b8b6dc 100644
--- a/packages/basemap/setup.py
+++ b/packages/basemap/setup.py
@@ -37,27 +37,33 @@ def get_geos_install_prefix():
         candidates = [os.path.expanduser("~/local"), os.path.expanduser("~"),
                       "/usr/local", "/usr", "/opt/local", "/opt", "/sw"]
 
+    # Prepare filename pattern to find the GEOS library.
+    extensions = {"win32": "dll", "cygwin": "dll", "darwin": "dylib"}
+    libext = extensions.get(sys.platform, "so*")
+    libname = "*geos_c*.{0}".format(libext)
+    libdirs = ["bin", "lib", "lib/x86_64-linux-gnu", "lib64"]
+
     for prefix in candidates:
         libfiles = []
-        libdirs = ["bin", "lib", "lib/x86_64-linux-gnu", "lib64"]
-        libext = "dll" if os.name == "nt" else "so"
-        libcode = "{0}geos_c".format("" if os.name == "nt" else "lib")
-        libname = "{0}*.{1}*".format(libcode, libext)
         for libdir in libdirs:
             libfiles.extend(glob.glob(os.path.join(prefix, libdir, libname)))
         hfile = os.path.join(prefix, "include", "geos_c.h")
         if os.path.isfile(hfile) and libfiles:
             return prefix
 
-    warnings.warn(" ".join([
-        "Cannot find GEOS library and/or headers in standard locations",
-        "('{0}'). Please install the corresponding packages using your",
-        "software management system or set the environment variable",
-        "GEOS_DIR to point to the location where GEOS is installed",
-        "(for example, if 'geos_c.h' is in '/usr/local/include'",
-        "and 'libgeos_c' is in '/usr/local/lib', then you need to",
-        "set GEOS_DIR to '/usr/local'",
-    ]).format("', '".join(candidates)), RuntimeWarning)
+    # At this point, the GEOS library was not found, so we throw a warning if
+    # the user is trying to build the library.
+    build_cmds = ("bdist_wheel", "build", "install")
+    if any(cmd in sys.argv[1:] for cmd in build_cmds):
+        warnings.warn(" ".join([
+            "Cannot find GEOS library and/or headers in standard locations",
+            "('{0}'). Please install the corresponding packages using your",
+            "software management system or set the environment variable",
+            "GEOS_DIR to point to the location where GEOS is installed",
+            "(for example, if 'geos_c.h' is in '/usr/local/include'",
+            "and 'libgeos_c' is in '/usr/local/lib', then you need to",
+            "set GEOS_DIR to '/usr/local'",
+        ]).format("', '".join(candidates)), RuntimeWarning)
     return None
 
 
@@ -94,7 +100,9 @@ def run(self):
         import numpy
         include_dirs.append(numpy.get_include())
     except ImportError as err:
-        warnings.warn("unable to locate NumPy headers", RuntimeWarning)
+        build_cmds = ("bdist_wheel", "build", "install")
+        if any(cmd in sys.argv[1:] for cmd in build_cmds):
+            warnings.warn("unable to locate NumPy headers", RuntimeWarning)
 
 # Define GEOS include, library and runtime dirs.
 geos_install_prefix = get_geos_install_prefix()
diff --git a/packages/basemap/utils/GeosLibrary.py b/packages/basemap/utils/GeosLibrary.py
index ffbcfd1f4..c7e9460e0 100644
--- a/packages/basemap/utils/GeosLibrary.py
+++ b/packages/basemap/utils/GeosLibrary.py
@@ -147,12 +147,24 @@ def extract(self, overwrite=True):
             for line in lines:
                 fd.write(line.replace(oldtext, newtext).encode())
 
-        # The SVN revision file is not created on the fly before 3.6.0.
-        svn_hfile = os.path.join(zipfold, "geos_svn_revision.h")
-        if self.version_tuple < (3, 6, 0) and not os.path.exists(svn_hfile):
-            with io.open(svn_hfile, "wb") as fd:
-                text = "#define GEOS_SVN_REVISION 0"
-                fd.write(text.encode())
+        # Apply specific patches for GEOS < 3.6.0.
+        if self.version_tuple < (3, 6, 0):
+            # The SVN revision file is not created on the fly before 3.6.0.
+            svn_hfile = os.path.join(zipfold, "geos_svn_revision.h")
+            if not os.path.exists(svn_hfile):
+                with io.open(svn_hfile, "wb") as fd:
+                    text = "#define GEOS_SVN_REVISION 0"
+                    fd.write(text.encode())
+            # Reduce warnings when compiling with `nmake` on Windows.
+            cmakefile = os.path.join(zipfold, "CMakeLists.txt")
+            if os.path.exists(cmakefile):
+                with io.open(cmakefile, "r", encoding="utf-8") as fd:
+                    lines = fd.readlines()
+                with io.open(cmakefile, "wb") as fd:
+                    oldtext = 'string(REGEX REPLACE "/W[0-9]" "/W4"'
+                    newtext = oldtext.replace("W4", "W1")
+                    for line in lines:
+                        fd.write(line.replace(oldtext, newtext).encode())
 
     def build(self, installdir=None, njobs=1):
         """Build and install GEOS from source."""
@@ -191,7 +203,7 @@ def build(self, installdir=None, njobs=1):
             build_opts.extend([
                 "--",
                 "WIN64={0}".format("YES" if win64 else "NO"),
-                "BUILD_BATCH={0}".format("YES" if njobs > 1 else "NO")
+                "BUILD_BATCH={0}".format("YES" if njobs > 1 else "NO"),
             ])
         else:
             build_opts = ["-j", "{0:d}".format(njobs)] + build_opts