Katahdin Loop Road Overlook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Katahdin Loop Road Overlook clear sky chart from 2005-11-06 to 2026-04-17.

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	17% 10% 3 8% 5% 5% 5% 4 6% 7% 32%	130958
	Night	16% 9% 3 8% 5% 5% 5% 4 5% 7% 34%	131284
Transparency	Day	50% 6% 13% 20% 11% 1	134445
	Night	49% 6% 13% 20% 11% 1	135885
Seeing	Day	25% 18% 30% 19% 7% 1	17619
	Night	23% 15% 31% 24% 7%	25967

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	11% 12% 4 11% 5% 5% 4 3 5% 5% 34%	4452
	11th to 20th	Day	11% 14% 6% 12% 6% 5% 5% 4 5% 6% 26%	4650
	21st to end	Day	6% 9% 3 10% 6% 6% 7% 4 6% 6% 35%	5124
February	1st to 10th	Day	11% 11% 4 10% 7% 7% 5% 4 6% 7% 27%	1868
	11th to 20th	Day	12% 11% 4 12% 8% 5% 4 3 6% 6% 29%	1924
	21st to end	Day	12% 11% 4 9% 6% 5% 5% 4 6% 5% 33%	1730
March	1st to 10th	Day	20% 15% 4 9% 5% 4 4 4 4 5% 27%	4609
	11th to 20th	Day	15% 16% 5% 8% 5% 4 5% 4 5% 5% 28%	5090
	21st to end	Day	21% 13% 3 7% 5% 5% 4 3 5% 6% 27%	5587
April	1st to 10th	Day	20% 12% 4 8% 5% 4 5% 4 5% 6% 27%	2509
	11th to 20th	Day	20% 10% 2 8% 5% 4 4 3 4 6% 33%	2645
	21st to end	Day	21% 11% 2 8% 4 4 5% 3 4 5% 33%	2600
May	1st to 10th	Day	24% 11% 3 8% 5% 5% 5% 4 5% 5% 25%	5886
	11th to 20th	Day	23% 10% 3 7% 4 4 5% 4 5% 7% 28%	5968
	21st to end	Day	19% 9% 2 7% 6% 5% 6% 5% 6% 7% 28%	7402
June	1st to 10th	Day	22% 8% 3 7% 6% 4 5% 4 5% 7% 28%	3000
	11th to 20th	Day	18% 7% 2 6% 5% 4 4 4 6% 8% 33%	3000
	21st to end	Day	24% 9% 3 6% 5% 5% 6% 4 6% 7% 26%	3000
July	1st to 10th	Day	14% 7% 2 8% 6% 6% 7% 5% 8% 10% 27%	6820
	11th to 20th	Day	16% 7% 3 6% 5% 5% 5% 3 5% 8% 37%	6370
	21st to end	Day	12% 6% 2 6% 5% 5% 6% 5% 7% 9% 39%	6926
August	1st to 10th	Day	16% 6% 2 7% 6% 6% 6% 5% 7% 7% 32%	4245
	11th to 20th	Day	13% 9% 3 7% 6% 5% 5% 5% 6% 8% 32%	4175
	21st to end	Day	14% 6% 2 6% 4 5% 5% 4 7% 8% 39%	4675
September	1st to 10th	Day	12% 5% 2 5% 3 5% 5% 4 5% 8% 45%	2330
	11th to 20th	Day	14% 5% 2 6% 4 3 4 4 5% 6% 48%	2200
	21st to end	Day	16% 7% 2 7% 4 4 3 4 5% 7% 41%	2200
October	1st to 10th	Day	17% 8% 2 7% 4 4 4 3 4 7% 40%	2131
	11th to 20th	Day	19% 9% 3 7% 5% 4 4 3 6% 7% 33%	1960
	21st to end	Day	22% 10% 3 8% 5% 4 5% 4 5% 6% 28%	1980
November	1st to 10th	Day	18% 10% 2 7% 5% 5% 5% 4 5% 6% 34%	1851
	11th to 20th	Day	16% 9% 2 8% 5% 4 4 4 5% 8% 34%	1769
	21st to end	Day	19% 11% 3 7% 5% 3 4 4 6% 7% 31%	1680
December	1st to 10th	Day	16% 12% 4 9% 6% 5% 4 4 5% 7% 29%	2361
	11th to 20th	Day	19% 9% 3 6% 5% 4 4 3 5% 5% 36%	2688
	21st to end	Day	17% 11% 5% 8% 4 3 5% 4 5% 6% 32%	3553
January	1st to 10th	Night	9% 13% 5% 10% 6% 5% 5% 4 5% 6% 32%	8438
	11th to 20th	Night	11% 13% 5% 11% 7% 7% 7% 5% 6% 7% 22%	8235
	21st to end	Night	7% 9% 3 9% 6% 7% 7% 4 7% 6% 36%	9057
February	1st to 10th	Night	10% 12% 4 8% 6% 5% 5% 4 6% 7% 31%	2751
	11th to 20th	Night	10% 11% 5% 9% 7% 6% 5% 3 6% 8% 30%	2579
	21st to end	Night	13% 10% 3 9% 5% 5% 4 4 5% 6% 37%	2076
March	1st to 10th	Night	21% 12% 3 9% 5% 5% 4 4 5% 5% 28%	5450
	11th to 20th	Night	16% 10% 4 8% 5% 5% 5% 4 7% 7% 28%	5089
	21st to end	Night	23% 12% 3 6% 4 4 4 4 5% 8% 27%	5587
April	1st to 10th	Night	19% 12% 4 7% 5% 4 5% 4 4 5% 31%	2108
	11th to 20th	Night	19% 10% 2 6% 3 4 4 3 6% 6% 37%	1838
	21st to end	Night	22% 10% 3 8% 4 5% 4 3 5% 5% 31%	1800
May	1st to 10th	Night	24% 10% 3 8% 5% 4 4 4 5% 6% 27%	4054
	11th to 20th	Night	21% 8% 3 8% 5% 5% 5% 4 6% 7% 28%	3955
	21st to end	Night	17% 8% 2 5% 4 4 4 4 5% 8% 38%	3493
June	1st to 10th	Night	21% 8% 3 5% 5% 6% 5% 4 6% 6% 31%	1400
	11th to 20th	Night	14% 8% 2 6% 5% 5% 5% 4 6% 7% 37%	1400
	21st to end	Night	25% 8% 3 7% 5% 3 4 4 5% 6% 32%	1400
July	1st to 10th	Night	13% 6% 3 6% 4 5% 5% 4 7% 8% 38%	3160
	11th to 20th	Night	18% 7% 2 6% 4 4 4 4 5% 7% 39%	3586
	21st to end	Night	11% 6% 2 5% 4 4 5% 4 7% 9% 44%	3926
August	1st to 10th	Night	20% 5% 2 6% 5% 5% 5% 4 5% 7% 34%	2870
	11th to 20th	Night	15% 7% 2 7% 4 5% 6% 5% 6% 8% 36%	2872
	21st to end	Night	13% 5% 2 7% 4 4 4 4 5% 6% 48%	3223
September	1st to 10th	Night	13% 4 2 5% 3 4 5% 3 5% 8% 49%	2067
	11th to 20th	Night	13% 6% 2 5% 3 4 3 3 5% 7% 50%	2200
	21st to end	Night	16% 7% 3 5% 4 4 3 3 4 7% 43%	2200
October	1st to 10th	Night	17% 5% 2 5% 4 4 4 3 6% 7% 44%	2268
	11th to 20th	Night	17% 7% 2 6% 5% 5% 4 4 5% 7% 38%	2435
	21st to end	Night	22% 9% 2 6% 4 4 4 4 5% 7% 33%	2860
November	1st to 10th	Night	18% 7% 3 6% 4 4 5% 4 6% 8% 35%	2667
	11th to 20th	Night	16% 7% 3 8% 4 4 4 4 5% 7% 37%	2848
	21st to end	Night	17% 10% 3 7% 4 4 4 4 6% 7% 33%	2940
December	1st to 10th	Night	13% 12% 3 8% 5% 5% 6% 4 6% 7% 31%	5044
	11th to 20th	Night	21% 9% 3 7% 4 4 4 3 4 5% 34%	5741
	21st to end	Night	17% 10% 4 8% 5% 5% 4 3 4 6% 34%	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	51% 4 12% 22% 9% 1	4453
	11th to 20th	Day	57% 5% 9% 20% 8% 1	4680
	21st to end	Day	45% 6% 10% 17% 19% 3	5124
February	1st to 10th	Day	55% 5% 12% 16% 9% 3	1868
	11th to 20th	Day	55% 5% 12% 16% 11% 1	1932
	21st to end	Day	52% 6% 8% 20% 12% 3	1730
March	1st to 10th	Day	59% 4 7% 9% 16% 4	4612
	11th to 20th	Day	56% 6% 16% 12% 8% 1	5090
	21st to end	Day	57% 4 6% 18% 13% 3	5587
April	1st to 10th	Day	57% 5% 10% 15% 11% 2	2509
	11th to 20th	Day	52% 4 10% 19% 13% 2	2645
	21st to end	Day	53% 4 9% 19% 11% 4	2600
May	1st to 10th	Day	58% 7% 9% 18% 8% 1	5897
	11th to 20th	Day	54% 7% 13% 18% 6% 3	5972
	21st to end	Day	51% 8% 12% 15% 12% 1	7402
June	1st to 10th	Day	54% 6% 13% 17% 9% 1	3000
	11th to 20th	Day	47% 6% 12% 21% 12% 2	3000
	21st to end	Day	55% 8% 12% 15% 9% 1	3000
July	1st to 10th	Day	47% 7% 19% 18% 8%	6745
	11th to 20th	Day	44% 6% 14% 28% 9%	6294
	21st to end	Day	40% 7% 14% 29% 10%	6728
August	1st to 10th	Day	47% 8% 15% 24% 7%	4231
	11th to 20th	Day	47% 7% 18% 22% 6%	4214
	21st to end	Day	41% 6% 16% 24% 13%	4675
September	1st to 10th	Day	38% 7% 13% 26% 15% 1	2330
	11th to 20th	Day	36% 5% 12% 29% 16% 1	2200
	21st to end	Day	41% 6% 11% 27% 14% 1	2200
October	1st to 10th	Day	51% 5% 12% 24% 8%	3469
	11th to 20th	Day	45% 4 12% 29% 10%	3176
	21st to end	Day	41% 5% 16% 20% 17% 1	3180
November	1st to 10th	Day	52% 5% 13% 19% 10% 1	1851
	11th to 20th	Day	50% 6% 13% 20% 10% 2	1769
	21st to end	Day	54% 7% 17% 17% 5%	1680
December	1st to 10th	Day	54% 5% 16% 13% 11%	2361
	11th to 20th	Day	48% 6% 13% 15% 13% 6%	2688
	21st to end	Day	52% 5% 12% 15% 12% 4	3553
January	1st to 10th	Night	52% 5% 15% 18% 9%	8438
	11th to 20th	Night	58% 6% 13% 15% 7% 1	8280
	21st to end	Night	46% 6% 9% 20% 16% 3	9057
February	1st to 10th	Night	51% 6% 12% 20% 10% 2	2751
	11th to 20th	Night	52% 6% 13% 18% 10% 2	2582
	21st to end	Night	49% 5% 10% 21% 13% 2	2076
March	1st to 10th	Night	59% 4 7% 14% 12% 3	5460
	11th to 20th	Night	52% 8% 18% 13% 8% 1	5090
	21st to end	Night	55% 5% 6% 19% 14% 1	5587
April	1st to 10th	Night	55% 6% 8% 15% 14% 3	2108
	11th to 20th	Night	48% 5% 10% 20% 15% 2	1838
	21st to end	Night	55% 4 9% 17% 12% 3	1800
May	1st to 10th	Night	56% 6% 12% 16% 9% 1	4060
	11th to 20th	Night	52% 9% 13% 20% 6% 1	3956
	21st to end	Night	42% 8% 15% 22% 12% 1	3494
June	1st to 10th	Night	52% 7% 11% 20% 9%	1400
	11th to 20th	Night	45% 8% 13% 21% 12% 1	1400
	21st to end	Night	52% 7% 14% 18% 9% 1	1400
July	1st to 10th	Night	42% 6% 20% 23% 8%	3125
	11th to 20th	Night	44% 6% 13% 30% 6%	3539
	21st to end	Night	36% 6% 19% 29% 9%	3809
August	1st to 10th	Night	48% 7% 16% 23% 6%	2860
	11th to 20th	Night	44% 7% 18% 21% 7% 1	2899
	21st to end	Night	37% 6% 15% 26% 16% 1	3223
September	1st to 10th	Night	33% 8% 15% 31% 12% 1	2067
	11th to 20th	Night	34% 6% 13% 32% 15% 1	2200
	21st to end	Night	40% 6% 13% 25% 15% 1	2200
October	1st to 10th	Night	44% 6% 12% 26% 12%	3710
	11th to 20th	Night	39% 5% 14% 30% 12%	3958
	21st to end	Night	41% 5% 19% 21% 13% 2	4610
November	1st to 10th	Night	46% 8% 15% 22% 9% 1	2667
	11th to 20th	Night	47% 6% 14% 20% 11% 2	2848
	21st to end	Night	50% 8% 16% 18% 8%	2940
December	1st to 10th	Night	51% 5% 14% 22% 8%	5044
	11th to 20th	Night	52% 5% 9% 18% 15% 1	5742
	21st to end	Night	52% 5% 12% 17% 13% 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	27% 23% 30% 16% 4	220
	11th to 20th	Day	31% 24% 32% 9% 3 1	220
	21st to end	Day	21% 21% 38% 12% 7%	242
February	1st to 10th	Day	24% 20% 35% 16% 4	408
	11th to 20th	Day	26% 27% 31% 14% 2	469
	21st to end	Day	24% 27% 31% 15% 2	446
March	1st to 10th	Day	29% 25% 30% 14% 2	540
	11th to 20th	Day	28% 25% 27% 16% 4	540
	21st to end	Day	31% 23% 25% 16% 4 1	594
April	1st to 10th	Day	36% 21% 26% 13% 3 1	540
	11th to 20th	Day	34% 22% 28% 11% 5% 1	516
	21st to end	Day	33% 23% 28% 12% 4 1	500
May	1st to 10th	Day	33% 17% 32% 14% 3 1	503
	11th to 20th	Day	28% 20% 28% 17% 5% 1	527
	21st to end	Day	25% 19% 31% 19% 5% 1	766
June	1st to 10th	Day	27% 17% 31% 17% 7% 1	730
	11th to 20th	Day	24% 15% 29% 22% 10% 1	730
	21st to end	Day	28% 12% 30% 21% 9% 1	730
July	1st to 10th	Day	17% 13% 34% 23% 11% 1	720
	11th to 20th	Day	19% 9% 41% 21% 9% 2	533
	21st to end	Day	18% 10% 34% 28% 9% 2	576
August	1st to 10th	Day	17% 10% 32% 27% 11% 3	526
	11th to 20th	Day	18% 10% 27% 29% 13% 3	519
	21st to end	Day	19% 13% 27% 28% 11% 3	583
September	1st to 10th	Day	15% 16% 29% 24% 13% 3	530
	11th to 20th	Day	18% 13% 25% 25% 13% 6%	530
	21st to end	Day	21% 14% 30% 20% 10% 4	530
October	1st to 10th	Day	20% 14% 29% 22% 10% 5%	491
	11th to 20th	Day	28% 16% 29% 17% 7% 3	420
	21st to end	Day	33% 17% 26% 19% 4	462
November	1st to 10th	Day	30% 16% 29% 19% 5%	425
	11th to 20th	Day	26% 21% 33% 14% 5% 1	430
	21st to end	Day	30% 21% 27% 17% 4	430
December	1st to 10th	Day	24% 18% 35% 19% 3	231
	11th to 20th	Day	35% 23% 28% 11% 3	220
	21st to end	Day	31% 23% 28% 14% 3	242
January	1st to 10th	Night	20% 22% 34% 20% 3	879
	11th to 20th	Night	24% 19% 33% 20% 4	840
	21st to end	Night	15% 21% 39% 21% 4	924
February	1st to 10th	Night	20% 21% 35% 20% 4	840
	11th to 20th	Night	22% 22% 37% 17% 3	823
	21st to end	Night	22% 17% 35% 23% 2	692
March	1st to 10th	Night	23% 18% 38% 20% 2	840
	11th to 20th	Night	24% 19% 32% 20% 5%	840
	21st to end	Night	23% 17% 34% 20% 5%	924
April	1st to 10th	Night	29% 16% 34% 17% 4	840
	11th to 20th	Night	26% 16% 33% 20% 6%	618
	21st to end	Night	33% 14% 30% 19% 5%	600
May	1st to 10th	Night	27% 13% 31% 25% 4 1	600
	11th to 20th	Night	25% 13% 33% 22% 6%	566
	21st to end	Night	20% 9% 37% 27% 6%	433
June	1st to 10th	Night	26% 9% 31% 28% 7%	400
	11th to 20th	Night	17% 10% 29% 33% 11%	400
	21st to end	Night	28% 7% 25% 34% 7%	400
July	1st to 10th	Night	19% 5% 31% 34% 10%	390
	11th to 20th	Night	20% 4 28% 37% 12%	388
	21st to end	Night	19% 5% 25% 38% 13%	438
August	1st to 10th	Night	19% 5% 24% 37% 15%	565
	11th to 20th	Night	16% 6% 23% 38% 17% 1	592
	21st to end	Night	15% 8% 26% 35% 15% 1	660
September	1st to 10th	Night	15% 7% 33% 30% 15% 1	777
	11th to 20th	Night	16% 11% 25% 32% 15% 2	800
	21st to end	Night	20% 9% 30% 26% 14% 1	800
October	1st to 10th	Night	22% 11% 25% 29% 12% 1	800
	11th to 20th	Night	23% 11% 31% 25% 10% 1	800
	21st to end	Night	28% 17% 28% 23% 4	880
November	1st to 10th	Night	27% 13% 31% 22% 6%	820
	11th to 20th	Night	23% 18% 29% 22% 7% 1	903
	21st to end	Night	26% 21% 27% 21% 5%	950
December	1st to 10th	Night	27% 14% 35% 21% 3 1	950
	11th to 20th	Night	27% 20% 31% 19% 3	950
	21st to end	Night	27% 18% 33% 18% 4	1045

Page generated at 2026-04-14 02:44:28. Version ac07

Copyright © 2026 Attilla Danko.