May arrives tomorrow with the promise of a spectacular week. OK, so there may be a bit of a thunderstorm overnight Tuesday into Wednesday. But you'll be home in bed, and only the flowers and the new grass will be out there to deal with it.

The rest of the week promises to be sun-blessed and mild, with daytime highs in the upper 60s and 70s. No charge. Just enjoy.

In the weather records, May in Baltimore comes with average daytime highs rising through the 70s, from 69 degrees in May Day, to 79 degrees by month's end. The average lows at BWI run from 47 degrees on the 1st to 57 degrees on the 31st.

We all know the weather can, and probably will bring more impressive extremes. The record highs are all in the 90s, with the exception of May 1 (89 degrees) and May 2 (88). The hottest May days on record for Baltimore reached 98 degrees, on May 19, 1962 and again on May 30, 1991.

Record cold for May was the 32-degree day that occurred on May 11, 1966. Snow can fall in May. But the only record of it are the traces that fell on May 1, 1963 and on May 9, 1923 - the latest snowfall on record for Baltimore.

May's arrival, of course, means that April 2007 slips into the record books. It was a cool one, but moderating weather late in the month saved us from setting a new record for cold April. 

We still have to add today's average to the calculation. But it appears this month will end with an average temperature of around 50.9 degrees. That would make this the 7th coolest on record since the official weather station moved to BWI in 1950. The last April to end up cooler than that was 25 years ago, in 1982, when we clocked an average of 50.7 degrees. The coolest April in that period averaged 49.5 degrees, in 1966.

The low average temperature can be laid to the persistently cold weather we saw early in April. We had a solid week - from the 5th to the 11th - with average daily temperatures 10 degrees or more below the long-term averages. The month's low was a 26-degree morning on the 9th. Things didn't really warm up until the third week in April, with a string of days in the 80s. before the recent cool-off. The month's high temperature was 85 degrees, on the 23rd.

Rainfall during April totaled an even 5 inches. That was more than 2 inches above the long-term average. You can atrribute all of it to the soaking we received on the 14th and 15th, when 2.74 inches fell at BWI.