BBT Question

I started charting my new cycle. I missed charting during the first week last cycle so not sure if this is normal. During this cycle the first day on my period my temp was low (97.3), then went up to 98.2, then went down again to 97.3, and on cd 4 (today) it went up to 99.5. wondering if this is normal during menstrual cycle? it was a light cycle