Black Coffee and high BP

Does black coffee consumption affect blood pressure readings and make it high? I've noticed by BP readings to be high lately and not sure if black coffee is causing it. My systole is around 120-128 but the diastole shoots up to 90 from morning to noon. I consume coffee around 8AM. But when i test BP again in the evening, it reads normal 120s/80s. Not clear if caffeine is the cause. Can someone comment on this?