Damariscotta River Association
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Damariscotta River Association clear sky chart from 2005-11-06 to 2024-01-16.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	18% 7% 3 5% 5% 3 4 4 5% 7% 39%	74577
	Night	19% 8% 3 5% 5% 3 4 4 5% 6% 39%	75200
Transparency	Day	44% 7% 12% 22% 14% 2	74284
	Night	46% 6% 11% 21% 14% 2	75029
Seeing	Day	22% 14% 33% 22% 8% 2	14260
	Night	22% 12% 30% 25% 9% 1	23029

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	15% 7% 3 5% 6% 3 5% 3 4 6% 41%	1517
	11th to 20th	Day	21% 8% 3 5% 4 3 4 3 5% 6% 38%	1480
	21st to end	Day	14% 10% 3 7% 5% 2 5% 4 4 6% 41%	1588
February	1st to 10th	Day	18% 11% 2 5% 5% 4 4 5% 4 7% 35%	1620
	11th to 20th	Day	14% 8% 4 5% 6% 2 4 6% 5% 7% 37%	1716
	21st to end	Day	16% 10% 4 6% 5% 3 6% 5% 5% 5% 35%	1480
March	1st to 10th	Day	17% 9% 3 5% 5% 3 5% 4 5% 7% 38%	1797
	11th to 20th	Day	18% 6% 3 6% 5% 3 3 3 5% 6% 42%	1964
	21st to end	Day	18% 8% 3 5% 6% 3 4 4 4 5% 41%	2196
April	1st to 10th	Day	20% 9% 4 6% 5% 3 4 4 4 6% 35%	2160
	11th to 20th	Day	20% 5% 3 4 5% 3 4 4 5% 7% 39%	2252
	21st to end	Day	23% 7% 4 6% 5% 4 4 4 5% 6% 34%	2340
May	1st to 10th	Day	24% 7% 3 6% 6% 3 4 3 4 6% 33%	2340
	11th to 20th	Day	20% 7% 3 6% 5% 3 4 4 5% 7% 38%	2301
	21st to end	Day	19% 6% 3 5% 4 3 5% 5% 6% 7% 37%	2719
June	1st to 10th	Day	22% 7% 2 6% 5% 3 4 5% 5% 8% 33%	2614
	11th to 20th	Day	18% 6% 3 4 5% 3 5% 5% 5% 8% 38%	2700
	21st to end	Day	23% 7% 2 5% 5% 3 5% 5% 6% 7% 31%	2595
July	1st to 10th	Day	17% 6% 2 5% 4 2 5% 5% 6% 9% 38%	2520
	11th to 20th	Day	14% 7% 2 5% 5% 3 5% 6% 7% 9% 37%	2520
	21st to end	Day	14% 5% 2 4 5% 4 6% 6% 7% 9% 38%	2726
August	1st to 10th	Day	13% 6% 2 4 4 3 6% 6% 6% 8% 41%	2327
	11th to 20th	Day	14% 6% 3 5% 4 4 5% 6% 7% 8% 38%	2304
	21st to end	Day	11% 5% 3 5% 4 3 5% 5% 6% 8% 46%	2512
September	1st to 10th	Day	12% 5% 2 4 5% 3 4 4 6% 8% 47%	2095
	11th to 20th	Day	13% 6% 2 4 3 3 3 3 4 6% 54%	1980
	21st to end	Day	17% 7% 2 5% 3 3 4 3 4 6% 45%	1980
October	1st to 10th	Day	18% 7% 2 6% 5% 3 4 4 4 6% 41%	1964
	11th to 20th	Day	18% 6% 3 5% 5% 3 5% 3 4 6% 42%	1757
	21st to end	Day	23% 8% 3 5% 4 3 4 4 4 5% 39%	1782
November	1st to 10th	Day	17% 6% 2 5% 5% 3 3 3 5% 6% 47%	1671
	11th to 20th	Day	21% 4 2 4 4 2 3 4 5% 6% 45%	1710
	21st to end	Day	21% 7% 3 5% 4 2 2 3 4 6% 43%	1606
December	1st to 10th	Day	22% 8% 3 7% 5% 2 4 4 3 5% 38%	1397
	11th to 20th	Day	22% 9% 3 5% 3 2 3 4 3 5% 41%	1668
	21st to end	Day	25% 9% 3 5% 6% 3 4 4 4 5% 31%	2679
January	1st to 10th	Night	16% 9% 3 5% 4 3 4 5% 5% 7% 40%	2649
	11th to 20th	Night	18% 11% 4 6% 6% 4 4 4 5% 6% 32%	2602
	21st to end	Night	13% 9% 3 6% 6% 3 4 5% 5% 6% 42%	2768
February	1st to 10th	Night	18% 9% 4 6% 5% 4 5% 4 5% 7% 34%	2340
	11th to 20th	Night	15% 8% 4 6% 6% 3 5% 5% 5% 5% 39%	2125
	21st to end	Night	14% 9% 4 6% 5% 2 4 4 4 6% 41%	1776
March	1st to 10th	Night	16% 12% 3 5% 5% 3 5% 4 4 5% 39%	2150
	11th to 20th	Night	18% 7% 3 6% 6% 4 4 4 5% 6% 36%	1994
	21st to end	Night	19% 8% 3 5% 4 3 4 3 4 6% 42%	2159
April	1st to 10th	Night	23% 9% 3 5% 5% 3 5% 4 4 6% 34%	1800
	11th to 20th	Night	19% 6% 3 4 5% 3 5% 4 6% 7% 38%	1656
	21st to end	Night	23% 9% 3 5% 5% 3 4 4 5% 6% 34%	1620
May	1st to 10th	Night	21% 8% 4 6% 6% 3 5% 6% 6% 6% 30%	1620
	11th to 20th	Night	23% 7% 3 5% 5% 3 5% 5% 6% 7% 31%	1593
	21st to end	Night	21% 10% 3 5% 4 3 4 4 5% 7% 34%	1569
June	1st to 10th	Night	24% 7% 2 5% 5% 3 5% 5% 5% 7% 31%	1337
	11th to 20th	Night	18% 6% 3 6% 4 2 5% 5% 5% 8% 38%	1260
	21st to end	Night	24% 8% 2 5% 5% 4 4 5% 5% 8% 31%	1356
July	1st to 10th	Night	18% 6% 3 4 5% 3 6% 5% 5% 9% 35%	1440
	11th to 20th	Night	18% 6% 3 5% 6% 3 5% 4 6% 8% 36%	1440
	21st to end	Night	15% 6% 3 6% 5% 3 5% 5% 7% 9% 36%	1574
August	1st to 10th	Night	13% 7% 2 6% 4 3 5% 5% 4 9% 41%	1610
	11th to 20th	Night	14% 8% 2 6% 6% 3 5% 5% 6% 8% 36%	1596
	21st to end	Night	14% 5% 2 4 4 3 4 4 5% 8% 47%	1842
September	1st to 10th	Night	13% 5% 3 5% 4 2 5% 5% 4 7% 47%	1864
	11th to 20th	Night	16% 7% 2 4 3 2 3 3 4 6% 52%	1980
	21st to end	Night	16% 4 2 3 5% 3 4 4 5% 7% 47%	1980
October	1st to 10th	Night	18% 8% 2 4 5% 3 4 5% 5% 7% 39%	1994
	11th to 20th	Night	18% 6% 2 5% 5% 3 4 5% 5% 7% 42%	2200
	21st to end	Night	26% 7% 2 4 5% 3 4 4 4 6% 37%	2574
November	1st to 10th	Night	18% 5% 2 5% 5% 3 3 4 4 6% 44%	2407
	11th to 20th	Night	18% 6% 2 4 4 3 4 5% 4 6% 43%	2470
	21st to end	Night	17% 7% 2 5% 5% 3 4 5% 4 6% 42%	2569
December	1st to 10th	Night	22% 10% 3 5% 5% 3 4 4 4 5% 36%	2779
	11th to 20th	Night	23% 6% 2 3 4 2 4 3 4 6% 41%	3531
	21st to end	Night	25% 9% 3 6% 5% 2 4 3 4 6% 35%	4976

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	44% 5% 11% 23% 16% 1	1518
	11th to 20th	Day	48% 6% 12% 20% 11% 3	1480
	21st to end	Day	44% 5% 11% 22% 16% 2	1588
February	1st to 10th	Day	49% 6% 11% 20% 13% 2	1620
	11th to 20th	Day	45% 7% 13% 19% 13% 3	1725
	21st to end	Day	49% 5% 10% 19% 13% 4	1480
March	1st to 10th	Day	45% 5% 14% 18% 14% 4	1800
	11th to 20th	Day	42% 5% 10% 22% 17% 4	1964
	21st to end	Day	44% 6% 10% 17% 17% 6%	2196
April	1st to 10th	Day	49% 5% 10% 17% 15% 4	2160
	11th to 20th	Day	43% 6% 11% 22% 15% 3	2252
	21st to end	Day	51% 5% 9% 18% 13% 4	2340
May	1st to 10th	Day	51% 6% 8% 19% 14% 2	2340
	11th to 20th	Day	45% 6% 10% 21% 16% 2	2305
	21st to end	Day	45% 9% 13% 20% 11% 2	2719
June	1st to 10th	Day	49% 7% 15% 20% 9%	2614
	11th to 20th	Day	43% 7% 12% 20% 15% 2	2700
	21st to end	Day	49% 9% 11% 20% 9% 1	2595
July	1st to 10th	Day	40% 9% 14% 24% 13%	2450
	11th to 20th	Day	41% 8% 16% 25% 10% 1	2445
	21st to end	Day	38% 10% 17% 23% 12% 1	2574
August	1st to 10th	Day	37% 8% 19% 26% 9%	2314
	11th to 20th	Day	39% 9% 16% 24% 12%	2304
	21st to end	Day	33% 8% 15% 24% 18% 1	2512
September	1st to 10th	Day	34% 7% 15% 26% 17% 1	2095
	11th to 20th	Day	32% 6% 12% 27% 21% 2	1980
	21st to end	Day	40% 6% 9% 27% 17% 1	1980
October	1st to 10th	Day	44% 6% 10% 24% 14% 2	1964
	11th to 20th	Day	43% 4 15% 27% 11% 1	1757
	21st to end	Day	48% 5% 10% 21% 14% 2	1782
November	1st to 10th	Day	39% 5% 13% 25% 16% 2	1671
	11th to 20th	Day	40% 5% 10% 23% 18% 3	1710
	21st to end	Day	43% 4 18% 22% 12% 1	1606
December	1st to 10th	Day	50% 5% 10% 21% 12% 1	1397
	11th to 20th	Day	46% 5% 9% 21% 14% 4	1668
	21st to end	Day	55% 7% 10% 17% 9% 3	2679
January	1st to 10th	Night	44% 5% 13% 23% 13% 2	2649
	11th to 20th	Night	53% 7% 12% 17% 10% 2	2602
	21st to end	Night	43% 5% 11% 22% 16% 2	2768
February	1st to 10th	Night	50% 5% 11% 18% 13% 2	2340
	11th to 20th	Night	48% 5% 9% 20% 15% 3	2127
	21st to end	Night	45% 5% 10% 21% 15% 4	1776
March	1st to 10th	Night	48% 4 8% 21% 16% 3	2160
	11th to 20th	Night	48% 5% 11% 18% 14% 4	1995
	21st to end	Night	44% 4 9% 19% 19% 5%	2159
April	1st to 10th	Night	51% 4 8% 17% 16% 4	1800
	11th to 20th	Night	44% 6% 10% 23% 16% 2	1656
	21st to end	Night	51% 5% 12% 17% 12% 4	1620
May	1st to 10th	Night	52% 7% 9% 17% 13% 2	1620
	11th to 20th	Night	51% 7% 9% 17% 12% 3	1594
	21st to end	Night	51% 7% 10% 18% 13% 1	1570
June	1st to 10th	Night	53% 6% 11% 20% 9% 1	1337
	11th to 20th	Night	45% 7% 13% 20% 14% 2	1260
	21st to end	Night	51% 7% 13% 19% 10%	1356
July	1st to 10th	Night	44% 8% 14% 20% 13% 1	1400
	11th to 20th	Night	44% 8% 14% 24% 10%	1392
	21st to end	Night	40% 10% 15% 24% 10% 1	1486
August	1st to 10th	Night	41% 8% 16% 25% 10% 1	1599
	11th to 20th	Night	44% 9% 15% 21% 12%	1596
	21st to end	Night	36% 7% 11% 27% 18% 1	1842
September	1st to 10th	Night	35% 8% 12% 28% 16% 1	1864
	11th to 20th	Night	36% 5% 11% 26% 20% 2	1980
	21st to end	Night	37% 6% 11% 29% 15% 2	1980
October	1st to 10th	Night	44% 7% 11% 23% 14% 2	1994
	11th to 20th	Night	41% 6% 13% 26% 13% 1	2200
	21st to end	Night	48% 6% 11% 20% 14% 1	2574
November	1st to 10th	Night	41% 6% 11% 26% 15% 1	2407
	11th to 20th	Night	41% 5% 11% 22% 18% 2	2470
	21st to end	Night	43% 6% 15% 20% 15% 2	2569
December	1st to 10th	Night	51% 5% 10% 21% 12% 1	2779
	11th to 20th	Night	45% 5% 11% 21% 17% 1	3532
	21st to end	Night	51% 6% 12% 18% 13% 1	4976

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	26% 22% 29% 18% 4	180
	11th to 20th	Day	29% 17% 34% 17% 2 1	170
	21st to end	Day	17% 24% 34% 22% 3	180
February	1st to 10th	Day	27% 20% 33% 17% 2	340
	11th to 20th	Day	24% 24% 37% 14% 1	402
	21st to end	Day	25% 19% 35% 18% 3	346
March	1st to 10th	Day	23% 18% 42% 15% 3	420
	11th to 20th	Day	21% 23% 38% 15% 3 1	420
	21st to end	Day	24% 22% 31% 15% 6% 2	462
April	1st to 10th	Day	27% 23% 29% 15% 5% 1	420
	11th to 20th	Day	24% 18% 35% 16% 6% 1	412
	21st to end	Day	28% 14% 37% 17% 3 1	420
May	1st to 10th	Day	27% 19% 31% 17% 4 1	423
	11th to 20th	Day	20% 15% 42% 16% 7% 1	447
	21st to end	Day	21% 15% 35% 22% 5% 1	485
June	1st to 10th	Day	21% 10% 34% 24% 9% 2	544
	11th to 20th	Day	20% 11% 33% 23% 11% 2	630
	21st to end	Day	22% 9% 30% 26% 10% 2	525
July	1st to 10th	Day	21% 7% 31% 30% 10% 2	445
	11th to 20th	Day	17% 6% 30% 32% 12% 2	444
	21st to end	Day	14% 6% 33% 32% 13% 2	488
August	1st to 10th	Day	13% 5% 32% 32% 16% 2	446
	11th to 20th	Day	16% 4 33% 30% 12% 5%	439
	21st to end	Day	14% 7% 31% 32% 14% 3	495
September	1st to 10th	Day	16% 6% 30% 31% 15% 2	450
	11th to 20th	Day	17% 10% 32% 25% 10% 5%	450
	21st to end	Day	18% 10% 32% 24% 10% 5%	450
October	1st to 10th	Day	22% 13% 23% 27% 11% 3	441
	11th to 20th	Day	20% 16% 29% 24% 9% 2	360
	21st to end	Day	30% 12% 29% 21% 7%	396
November	1st to 10th	Day	21% 15% 30% 25% 7% 2	365
	11th to 20th	Day	25% 17% 32% 20% 5% 1	370
	21st to end	Day	23% 23% 27% 19% 7% 1	370
December	1st to 10th	Day	25% 15% 38% 17% 4 1	247
	11th to 20th	Day	31% 21% 36% 9% 3 1	180
	21st to end	Day	29% 24% 31% 11% 4 1	198
January	1st to 10th	Night	21% 21% 35% 20% 4	760
	11th to 20th	Night	26% 21% 33% 16% 4	744
	21st to end	Night	19% 22% 36% 19% 3	792
February	1st to 10th	Night	23% 19% 36% 18% 3	720
	11th to 20th	Night	20% 22% 37% 18% 2	703
	21st to end	Night	21% 17% 39% 19% 5%	592
March	1st to 10th	Night	23% 18% 36% 21% 2	720
	11th to 20th	Night	23% 15% 35% 19% 7%	720
	21st to end	Night	23% 15% 34% 22% 6% 1	792
April	1st to 10th	Night	29% 15% 33% 18% 5% 1	720
	11th to 20th	Night	22% 10% 34% 28% 5% 1	592
	21st to end	Night	30% 10% 27% 26% 7% 1	540
May	1st to 10th	Night	25% 6% 30% 29% 8% 1	540
	11th to 20th	Night	25% 6% 34% 28% 6%	532
	21st to end	Night	26% 4 25% 33% 11% 1	408
June	1st to 10th	Night	26% 6% 21% 33% 13% 1	360
	11th to 20th	Night	21% 4 22% 37% 14% 1	360
	21st to end	Night	27% 5% 18% 40% 11%	360
July	1st to 10th	Night	22% 3 15% 42% 17%	350
	11th to 20th	Night	20% 3 18% 38% 19% 2	348
	21st to end	Night	18% 3 18% 40% 20% 1	394
August	1st to 10th	Night	16% 3 21% 42% 17% 1	536
	11th to 20th	Night	16% 4 19% 41% 17% 2	532
	21st to end	Night	15% 3 22% 37% 20% 2	654
September	1st to 10th	Night	15% 3 26% 35% 19% 2	720
	11th to 20th	Night	19% 7% 26% 25% 20% 3	720
	21st to end	Night	18% 5% 27% 30% 17% 2	720
October	1st to 10th	Night	22% 9% 22% 30% 16% 1	720
	11th to 20th	Night	20% 12% 31% 26% 10% 2	720
	21st to end	Night	30% 13% 29% 23% 6%	792
November	1st to 10th	Night	21% 10% 33% 26% 8% 1	740
	11th to 20th	Night	22% 15% 35% 21% 7% 1	760
	21st to end	Night	21% 20% 34% 20% 5%	807
December	1st to 10th	Night	27% 13% 40% 14% 6%	850
	11th to 20th	Night	25% 19% 35% 18% 3	850
	21st to end	Night	28% 17% 34% 18% 3	861

Page generated at 2024-01-13 09:37:56. Version ac07

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