Through April 26, NOAA's MLO average for the month is approximately 401.25 ppm. Here are the NOAA daily, weekly and monthly averages for the previous year as of April 26, 2014.
Compared to April, 2013, the NOAA/ESRL April, 2014 average may be as much as 2.80-2.95 ppm higher than last year. This reflects the trends of increasing atmospheric CO2 even without El Nino as a factor.
Scripps/Keeling Curve CO2:
The April, 2014 Scripps/Keeling Curve average CO2 through April 26, 2014 is 401.34 ppm. The hourly/daily graph of the last week has reflected individual hours as high as 402 ppm.
The Keeling Curve graph for the last month portrays the increase during the last 30 days.
With May usually reporting the highest monthly CO2 averge at Mauna Loa, May, 2014 may average CO2 readings over 403 ppm.