How to avoid AnnotationBbox image being clipped in matplotlib subplot

I'm plotting NYC water consumption overtime and am trying to annotate the plot with red heat wave images hovering over each year where there was a drought. However, the heat wave image is layered beneath the plot and is being clipped.

How can I "bring forward" the heatwave image so that is fully visible and not being clipped?

Here is my code:

# create the plot
fig, ax = plt.subplots(figsize=(11, 8))

# plot total consumption as a vertical bar chart
ax1 = fig.add_subplot(111)
bar = sns.barplot(x = df['year'], y = df['nyc_consumption_million_gallons_per_day'], color = 'b')
ax1.set_ylim([600, 1600])
ax1.grid(False)
ax1.set_ylabel('Total Consumption (Millions of Gallons per Day)', fontsize=11)
ax1.set_xlabel('')

# plot per capital consumption as a line
ax2 = ax1.twinx()
line = plt.plot(df['per_capita_gallons_per_person_per_day'], color='g')
ax2.set_ylim(100,240)
ax2.grid(False)
ax2.set_ylabel('Per Capita Consumption (Gallons per Person per Day)', fontsize=11)

# design properties
ax.get_yaxis().set_visible(False) # removes y axis from underlying figure
ax.get_xaxis().set_visible(False) # removes x axis from underlying figure

# make a legend
leg1 = plt.Rectangle((0,0),1,1,fc='b', edgecolor='none')
leg2 = plt.Rectangle((0,0),1,1,fc='g', edgecolor='none')

l = plt.legend([leg1, leg2], ['Total Consumption', 'Per Capita Consumption'],
               bbox_to_anchor=(1.0,1.01), ncol = 4, prop={'size':14})

# add title
title = ax.annotate("Water Consumption in New York City is Decreasing",
            (0,0), (-75, 530), textcoords='offset points', color='gray', fontsize=26, fontweight='heavy')

# add subtitle
sub = ax.annotate("History of average daily water consumption in the New York City Water Supply System",
            (0,0), (-75, 505), textcoords='offset points', color='gray', fontsize=16, style='italic')

# add heatwave symbols on top of years that had a drought
arr_hand = read_png(r"C:UsersWillDownloadsheat-symbol-hi.png")
imagebox = OffsetImage(arr_hand, zoom=0.9)
xy = [0.25, 0.45]               # coordinates to position this image

ab = AnnotationBbox(imagebox, xy,
    xybox=(30., 30.),
    xycoords='data',
    boxcoords="offset points", frameon=False)                                  
ax.add_artist(ab)

Here is the result: plot