Bar Harbor
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bar Harbor clear sky chart from 2005-11-06 to 2026-09-29.

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% 9% 3 6% 4 4 4 3 5% 7% 38%	148899
	Night	19% 10% 3 6% 4 4 4 3 5% 6% 36%	142567
Transparency	Day	45% 7% 13% 21% 13% 2	152435
	Night	47% 6% 12% 20% 13% 2	147121
Seeing	Day	22% 12% 30% 25% 9% 1	18438
	Night	24% 14% 28% 25% 9% 1	26591

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% 9% 3 8% 4 5% 5% 4 5% 6% 35%	4639
	11th to 20th	Day	16% 12% 3 6% 4 3 4 3 4 5% 39%	4650
	21st to end	Day	12% 10% 3 6% 3 4 4 3 5% 6% 43%	5397
February	1st to 10th	Day	15% 12% 3 6% 5% 4 5% 5% 6% 6% 32%	1890
	11th to 20th	Day	14% 8% 3 8% 4 5% 5% 4 6% 7% 37%	1929
	21st to end	Day	13% 10% 4 7% 5% 5% 5% 3 6% 6% 37%	1730
March	1st to 10th	Day	24% 11% 3 6% 4 4 4 4 5% 5% 31%	4669
	11th to 20th	Day	21% 11% 2 6% 4 4 4 3 5% 6% 35%	5090
	21st to end	Day	29% 9% 3 6% 4 3 4 3 5% 5% 30%	5587
April	1st to 10th	Day	20% 11% 2 6% 5% 4 4 4 5% 6% 35%	2454
	11th to 20th	Day	20% 8% 3 6% 4 3 3 3 5% 6% 38%	2702
	21st to end	Day	20% 9% 2 5% 4 4 4 3 5% 6% 37%	2730
May	1st to 10th	Day	27% 11% 3 7% 4 3 3 3 5% 6% 28%	7639
	11th to 20th	Day	17% 8% 3 7% 4 4 5% 4 5% 7% 36%	7625
	21st to end	Day	18% 9% 3 7% 4 5% 4 4 5% 6% 34%	9207
June	1st to 10th	Day	22% 8% 2 7% 5% 4 4 3 5% 7% 33%	3150
	11th to 20th	Day	19% 8% 2 5% 4 4 4 4 5% 7% 40%	3150
	21st to end	Day	25% 9% 2 7% 4 3 3 4 5% 6% 31%	3150
July	1st to 10th	Day	16% 8% 3 6% 4 5% 5% 4 6% 10% 33%	8648
	11th to 20th	Day	13% 9% 2 5% 3 3 4 3 5% 9% 43%	8280
	21st to end	Day	16% 7% 2 5% 3 3 4 3 6% 8% 43%	8701
August	1st to 10th	Day	16% 8% 2 7% 4 4 5% 4 5% 8% 37%	6015
	11th to 20th	Day	17% 8% 3 6% 5% 4 5% 3 6% 8% 35%	5953
	21st to end	Day	12% 6% 2 5% 4 3 3 3 5% 7% 49%	6594
September	1st to 10th	Day	12% 5% 2 5% 4 4 3 4 5% 7% 48%	2415
	11th to 20th	Day	13% 5% 2 5% 3 3 4 3 4 6% 53%	2310
	21st to end	Day	18% 6% 2 5% 4 3 4 3 5% 6% 44%	2288
October	1st to 10th	Day	16% 9% 2 6% 3 3 3 4 4 7% 43%	2120
	11th to 20th	Day	18% 7% 2 6% 4 3 3 4 5% 7% 42%	2000
	21st to end	Day	21% 9% 2 4 3 4 3 2 5% 6% 39%	2005
November	1st to 10th	Day	18% 6% 2 7% 4 4 3 3 5% 6% 41%	1851
	11th to 20th	Day	20% 6% 2 6% 3 3 4 4 5% 7% 42%	1812
	21st to end	Day	20% 10% 3 6% 4 3 4 3 4 6% 38%	1680
December	1st to 10th	Day	19% 10% 2 5% 2 3 4 3 5% 6% 42%	2598
	11th to 20th	Day	21% 8% 2 5% 3 3 4 3 4 5% 40%	2688
	21st to end	Day	20% 12% 4 6% 3 2 3 2 4 5% 38%	3553
January	1st to 10th	Night	12% 11% 4 8% 5% 4 4 3 4 6% 39%	8252
	11th to 20th	Night	17% 12% 4 9% 5% 4 4 3 5% 6% 30%	8235
	21st to end	Night	11% 10% 3 7% 4 4 4 4 6% 7% 41%	8781
February	1st to 10th	Night	18% 10% 3 7% 5% 4 5% 3 5% 7% 33%	2730
	11th to 20th	Night	14% 11% 3 7% 4 4 4 3 6% 6% 39%	2574
	21st to end	Night	15% 10% 3 6% 5% 4 4 3 5% 7% 38%	2076
March	1st to 10th	Night	26% 11% 3 6% 5% 4 3 2 4 5% 31%	5391
	11th to 20th	Night	17% 12% 3 7% 4 5% 5% 4 6% 7% 31%	5089
	21st to end	Night	28% 9% 2 6% 4 4 4 3 5% 6% 30%	5587
April	1st to 10th	Night	22% 12% 2 7% 4 4 3 3 5% 6% 33%	2163
	11th to 20th	Night	22% 9% 3 7% 5% 3 3 3 6% 7% 33%	1868
	21st to end	Night	23% 9% 3 6% 4 4 3 3 4 5% 34%	1890
May	1st to 10th	Night	29% 10% 3 7% 3 3 3 2 4 6% 30%	5259
	11th to 20th	Night	22% 9% 3 6% 4 4 4 3 5% 8% 32%	5235
	21st to end	Night	16% 11% 4 8% 5% 5% 4 3 5% 6% 33%	5027
June	1st to 10th	Night	24% 10% 2 5% 4 4 4 5% 4 8% 28%	1470
	11th to 20th	Night	19% 10% 3 5% 4 4 3 4 5% 7% 35%	1470
	21st to end	Night	27% 10% 3 6% 4 3 3 3 5% 6% 30%	1470
July	1st to 10th	Night	16% 11% 3 9% 5% 5% 6% 4 7% 7% 27%	4313
	11th to 20th	Night	18% 11% 2 5% 4 3 4 4 5% 7% 37%	4680
	21st to end	Night	16% 7% 2 5% 4 4 4 4 6% 8% 40%	5316
August	1st to 10th	Night	19% 11% 4 7% 4 4 5% 3 5% 7% 31%	4135
	11th to 20th	Night	18% 10% 3 7% 4 3 4 4 6% 8% 33%	4092
	21st to end	Night	14% 7% 2 6% 4 4 4 4 5% 8% 42%	4531
September	1st to 10th	Night	15% 5% 2 5% 3 3 4 3 5% 6% 48%	2200
	11th to 20th	Night	16% 6% 2 4 3 3 3 3 4 6% 50%	2310
	21st to end	Night	19% 6% 2 5% 3 3 3 4 5% 6% 44%	2289
October	1st to 10th	Night	19% 6% 2 5% 3 4 4 3 5% 6% 42%	2279
	11th to 20th	Night	19% 7% 2 6% 4 4 4 4 4 6% 42%	2400
	21st to end	Night	23% 9% 2 6% 4 3 4 3 4 6% 37%	2830
November	1st to 10th	Night	19% 5% 2 5% 3 4 4 4 4 6% 42%	2667
	11th to 20th	Night	17% 7% 2 6% 4 4 4 4 5% 6% 41%	2804
	21st to end	Night	19% 8% 2 6% 4 4 4 4 5% 7% 38%	2940
December	1st to 10th	Night	19% 9% 2 5% 4 3 4 4 6% 7% 36%	4806
	11th to 20th	Night	23% 8% 2 5% 3 3 3 3 4 5% 41%	5741
	21st to end	Night	22% 11% 3 6% 3 3 3 3 4 5% 37%	7667

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	48% 6% 13% 24% 9% 1	4640
	11th to 20th	Day	47% 6% 12% 21% 13% 2	4680
	21st to end	Day	42% 6% 11% 21% 17% 4	5397
February	1st to 10th	Day	52% 7% 12% 17% 10% 2	1890
	11th to 20th	Day	46% 7% 15% 17% 12% 2	1937
	21st to end	Day	46% 7% 11% 20% 11% 4	1730
March	1st to 10th	Day	53% 5% 10% 11% 15% 5%	4673
	11th to 20th	Day	48% 6% 16% 19% 10% 1	5090
	21st to end	Day	54% 5% 7% 16% 15% 3	5587
April	1st to 10th	Day	49% 5% 11% 17% 16% 3	2454
	11th to 20th	Day	44% 6% 11% 23% 13% 3	2702
	21st to end	Day	46% 6% 10% 19% 16% 3	2730
May	1st to 10th	Day	55% 7% 12% 17% 7% 1	7651
	11th to 20th	Day	45% 8% 15% 21% 9% 2	7629
	21st to end	Day	47% 9% 11% 20% 12% 1	9208
June	1st to 10th	Day	50% 7% 12% 21% 10%	3150
	11th to 20th	Day	45% 7% 12% 20% 14% 2	3150
	21st to end	Day	54% 6% 12% 17% 10% 2	3150
July	1st to 10th	Day	48% 8% 15% 20% 9%	8576
	11th to 20th	Day	40% 7% 15% 23% 14% 1	8205
	21st to end	Day	39% 7% 15% 24% 14% 1	8508
August	1st to 10th	Day	47% 8% 17% 19% 8% 1	6002
	11th to 20th	Day	44% 8% 18% 19% 10%	5992
	21st to end	Day	34% 7% 13% 26% 18% 1	6594
September	1st to 10th	Day	34% 7% 13% 27% 17% 2	2415
	11th to 20th	Day	33% 6% 12% 25% 21% 3	2310
	21st to end	Day	39% 7% 10% 26% 16% 2	2288
October	1st to 10th	Day	42% 8% 14% 22% 12% 1	3458
	11th to 20th	Day	30% 5% 10% 34% 20%	3240
	21st to end	Day	34% 5% 18% 23% 17% 3	3217
November	1st to 10th	Day	43% 7% 14% 23% 12% 1	1851
	11th to 20th	Day	42% 7% 10% 23% 16% 3	1812
	21st to end	Day	48% 6% 17% 21% 7% 1	1680
December	1st to 10th	Day	43% 7% 15% 22% 13% 1	2598
	11th to 20th	Day	47% 5% 14% 17% 12% 6%	2688
	21st to end	Day	50% 7% 11% 18% 11% 3	3553
January	1st to 10th	Night	46% 5% 14% 23% 11% 1	8252
	11th to 20th	Night	54% 7% 12% 17% 10% 1	8280
	21st to end	Night	43% 5% 11% 22% 17% 4	8781
February	1st to 10th	Night	52% 6% 13% 17% 11% 1	2730
	11th to 20th	Night	46% 7% 12% 19% 14% 2	2577
	21st to end	Night	47% 5% 10% 22% 13% 3	2076
March	1st to 10th	Night	56% 5% 8% 11% 13% 7%	5400
	11th to 20th	Night	47% 9% 21% 14% 7% 1	5090
	21st to end	Night	55% 4 7% 16% 16% 2	5587
April	1st to 10th	Night	52% 6% 9% 15% 16% 3	2163
	11th to 20th	Night	50% 5% 9% 20% 15% 2	1868
	21st to end	Night	52% 5% 10% 17% 14% 3	1890
May	1st to 10th	Night	57% 6% 13% 14% 10%	5265
	11th to 20th	Night	48% 8% 14% 19% 10% 1	5236
	21st to end	Night	50% 8% 12% 19% 12%	5028
June	1st to 10th	Night	52% 8% 11% 21% 8% 1	1470
	11th to 20th	Night	47% 8% 11% 20% 12% 2	1470
	21st to end	Night	55% 5% 10% 19% 9% 2	1470
July	1st to 10th	Night	53% 8% 12% 19% 7%	4275
	11th to 20th	Night	47% 7% 12% 22% 13%	4632
	21st to end	Night	42% 7% 14% 23% 13% 1	5195
August	1st to 10th	Night	53% 8% 11% 19% 8%	4123
	11th to 20th	Night	48% 8% 15% 21% 9%	4119
	21st to end	Night	39% 7% 15% 22% 16% 1	4531
September	1st to 10th	Night	36% 7% 13% 27% 17% 1	2200
	11th to 20th	Night	36% 5% 12% 26% 20% 2	2310
	21st to end	Night	39% 6% 11% 26% 17% 2	2289
October	1st to 10th	Night	39% 5% 15% 24% 15% 2	3721
	11th to 20th	Night	32% 5% 11% 28% 23% 1	3899
	21st to end	Night	39% 4 10% 29% 15% 2	4568
November	1st to 10th	Night	43% 6% 12% 24% 15% 1	2667
	11th to 20th	Night	45% 5% 13% 21% 14% 2	2804
	21st to end	Night	46% 7% 15% 19% 11% 1	2940
December	1st to 10th	Night	47% 6% 12% 24% 11%	4806
	11th to 20th	Night	46% 5% 13% 20% 14% 2	5742
	21st to end	Night	49% 7% 12% 17% 14% 1	7667

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	23% 30% 32% 11% 4	220
	11th to 20th	Day	28% 26% 26% 15% 3 1	220
	21st to end	Day	19% 24% 34% 18% 4	334
February	1st to 10th	Day	22% 24% 32% 18% 4	430
	11th to 20th	Day	22% 25% 37% 13% 3	472
	21st to end	Day	21% 20% 36% 20% 3	446
March	1st to 10th	Day	25% 21% 36% 16% 2	540
	11th to 20th	Day	23% 22% 32% 20% 4	540
	21st to end	Day	27% 19% 31% 17% 6% 1	594
April	1st to 10th	Day	28% 17% 36% 14% 3 1	540
	11th to 20th	Day	26% 15% 35% 19% 5%	532
	21st to end	Day	24% 9% 36% 24% 6% 1	540
May	1st to 10th	Day	24% 15% 33% 23% 4 1	543
	11th to 20th	Day	17% 9% 37% 28% 8% 1	567
	21st to end	Day	25% 7% 30% 26% 10% 1	753
June	1st to 10th	Day	23% 5% 28% 30% 13% 2	780
	11th to 20th	Day	23% 6% 26% 29% 13% 2	780
	21st to end	Day	28% 5% 24% 30% 11% 2	780
July	1st to 10th	Day	22% 4 26% 33% 14% 1	697
	11th to 20th	Day	20% 6% 23% 36% 14% 2	564
	21st to end	Day	17% 5% 23% 37% 15% 3	620
August	1st to 10th	Day	13% 5% 24% 36% 19% 2	566
	11th to 20th	Day	18% 4 21% 36% 17% 3	559
	21st to end	Day	16% 6% 23% 34% 19% 3	627
September	1st to 10th	Day	16% 4 26% 35% 17% 1	570
	11th to 20th	Day	16% 9% 27% 29% 13% 6%	570
	21st to end	Day	18% 5% 31% 28% 14% 3	562
October	1st to 10th	Day	17% 10% 25% 32% 15% 1	486
	11th to 20th	Day	19% 11% 33% 25% 10% 1	420
	21st to end	Day	27% 13% 31% 24% 5%	462
November	1st to 10th	Day	21% 19% 29% 23% 6% 1	425
	11th to 20th	Day	23% 22% 32% 18% 4 1	430
	21st to end	Day	26% 22% 30% 18% 4	430
December	1st to 10th	Day	27% 17% 34% 18% 4	377
	11th to 20th	Day	32% 24% 30% 12% 2	220
	21st to end	Day	28% 21% 31% 15% 5%	242
January	1st to 10th	Night	23% 24% 32% 17% 3	843
	11th to 20th	Night	27% 21% 32% 15% 4	840
	21st to end	Night	19% 27% 35% 17% 3	924
February	1st to 10th	Night	24% 23% 34% 15% 4	840
	11th to 20th	Night	22% 27% 32% 16% 3	823
	21st to end	Night	23% 19% 36% 19% 4	692
March	1st to 10th	Night	25% 18% 35% 20% 2	840
	11th to 20th	Night	23% 18% 31% 22% 6%	840
	21st to end	Night	25% 16% 32% 21% 6% 1	924
April	1st to 10th	Night	30% 14% 32% 20% 4	840
	11th to 20th	Night	27% 9% 32% 26% 6%	624
	21st to end	Night	29% 9% 27% 25% 8% 2	630
May	1st to 10th	Night	28% 6% 30% 26% 9% 2	630
	11th to 20th	Night	25% 5% 29% 32% 8%	622
	21st to end	Night	25% 5% 24% 33% 11% 2	565
June	1st to 10th	Night	30% 5% 17% 35% 12% 1	420
	11th to 20th	Night	23% 4 21% 35% 15% 1	420
	21st to end	Night	32% 2 15% 36% 14%	420
July	1st to 10th	Night	23% 3 17% 40% 16%	410
	11th to 20th	Night	25% 4 15% 38% 17% 1	408
	21st to end	Night	23% 2 15% 38% 19% 2	538
August	1st to 10th	Night	22% 2 15% 41% 19% 1	628
	11th to 20th	Night	20% 5% 15% 40% 19% 1	622
	21st to end	Night	17% 3 18% 37% 22% 3	693
September	1st to 10th	Night	17% 3 22% 37% 18% 2	808
	11th to 20th	Night	19% 5% 23% 30% 18% 5%	840
	21st to end	Night	20% 5% 24% 33% 15% 3	833
October	1st to 10th	Night	21% 8% 25% 28% 17% 2	800
	11th to 20th	Night	20% 12% 30% 24% 14% 2	800
	21st to end	Night	27% 16% 29% 22% 6%	880
November	1st to 10th	Night	23% 15% 28% 25% 8% 1	820
	11th to 20th	Night	21% 22% 29% 21% 6% 1	879
	21st to end	Night	24% 22% 32% 15% 6% 1	950
December	1st to 10th	Night	30% 18% 33% 16% 3	950
	11th to 20th	Night	27% 27% 30% 14% 2	950
	21st to end	Night	28% 22% 29% 18% 3	1045

Page generated at 2026-09-26 04:18:38. Version ac07

Copyright © 2026 Attilla Danko.