seaborn.pairplot can have its legend crushing on the right edge of the subplots on macOS. This shows a temporary solution.

seaborn_pairplot_legend_fix.py

import seaborn as sns

sns.set()

# turn on interactive mode, avoid-blocking
sns.plt.ion()

# take iris scatterplot matrix as an example
iris = sns.load_dataset("iris")

# plot with conda bulit matplotlib-1.5.3-np111py35_1 and seaborn-0.7.1-py35_0
# legend is crushing on the right edge of subplots
sns.pairplot(iris, hue="species")

# investigating the right margin of subplot parameters
sns.plt.gcf().subplotpars.right
# will return: 0.98875156054931335
# while the documented default value is 0.9, according to 
# http://matplotlib.org/api/figure_api.html#matplotlib.figure.SubplotParams
# the value of right margin might be changed by matplotlib.pyplot.tight_layout()?
 
# reset the right margin of subplot to its documented default value will temporarily solve the crushing issue.
sns.plt.gcf().subplots_adjust(right=0.9) # you can further reduce the value to separate legend and subplots.