This works:
start = datenum(2010,05,15,0,0,0);
fin=datenum(2010,05,30,23,0,0);
hrvct = start:(1/24):fin; % Create Hourly Dates
dtks = start+0.5:fin; % Ticks At Noon
dhv = datevec(dtks);
y = (0:length(hrvct)-1)*0.005-sin((0:length(hrvct)-1)/24*2*pi+0.25)*5+randn(size(hrvct))*0.05+20; % Create Y-Data
figure(1)
plot(hrvct, y)
grid
set(gca, 'XTick', dtks, 'XTickLabelRotation',30) % Label Rotation (R2014b)
datetick('x', 'mmm dd', 'keepticks')
xlabel('Time')
ylabel('Temperature (\circC)')
You have to have R2014b to use the 'XTickLabelRotation' property. Otherwise, either reduce your x-axis font size or use the text function to create a vector of rotated dates.
Example plot:
