Today is the first day of meteorological summer or the start of the warmest three months of the year. Unfortunately, if you were expecting warm weather, it’s not going to happen for a few days.

A Look Back At May
May ended on cool wet note, but only in the final few hours. Overall it was a dry and very warm month. This year Portland had 16 days of 70 degree weather or higher. This ties 1959 for the highest number in the record books. Back in 2005, a cool May, only 1 days reached 70 degrees, there are several years when it never reached 70, but these are from 1948 and earlier.

The last 8 days were particularly warm. The average high temperature of 81.3 degrees in Portland was higher than the average for July! This was a highly unusual stretch of warm weather in the month of May and included a 91 degree day. We finally are seeing some much needed rain, but it certainly waited until the final few hours of the month to fall. Prior to yesterday, many climatological sites from southern Maine to southern New England were about to set a record for their driest or one of the driest Mays. Now, this won’t even be one of the top 20 driest Mays, it was still dry, but not dramatic.

June Starts Wet
We have about another 36 hours of cool wet weather to go before things become more typical for June. The coldest high temperature recorded for June 1st in Portland was 51 degrees. If Portland only reaches 51 degrees, which is possible, this would tie June 1st 1992’s high temperature for the coldest daily high on record. As I have often said, weather in New England is about extremes and the averages don’t mean very much. Take the warmth of Saturday and the chill of today add them up and divide by two and that’s close to the actual average for this time of year.

Why So Cold?
The reason for the chill is basically due to the wind direction which dramatically shifted yesterday afternoon. After reaching the 70s on a southwest wind a flow of air off the cold Atlantic brought chilly marine air rapidly south into the area. The jet stream had been stuck in a configuration which kept warm and dry weather here and wet weather over Texas and Oklahoma. This looks to have shifted for now.

Drought Busting Rain
The weather map above shows the front stalled to our south. Overnight and into Tuesday small waves of energy will ride along this boundary and bring more rain to the region.

The radar prediction for Tuesday morning indicates showers and some heavier downpours are again possible. This will slow the morning commute and continue to add water to the ground which was becoming very dry.

Even with significant rain now, rivers are so low they could handle many more inches of rain. Here’s a chart for one spot on the Saco River.

Notice how far below flood stage this area is currently.
I suspect on Thursday, when the next drought monitor is issued, we will see some official improvement in the status of the drought. As of 7AM, much of the region has seen 1 to over 2 inches of rain. You can see some of the data below.

Seasonable Weather
The extended forecast indicates a return to temperatures in the 70s and a few chances of showers over the next 10 days. I don’t see any total washouts, but also the drought-like pattern seems to have broken for now.

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Once we get into June, it becomes increasingly less likely to see an all-day rain as most of our precipitation falls from showers.