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 2024-12-24.

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% 9% 3 8% 5% 5% 5% 4 6% 7% 32%	101784
	Night	17% 9% 3 7% 5% 5% 5% 4 5% 7% 34%	98379
Transparency	Day	50% 6% 13% 20% 10% 1	105289
	Night	48% 7% 14% 20% 10% 1	102964
Seeing	Day	25% 17% 30% 19% 7% 1	15944
	Night	23% 15% 31% 24% 7%	24217

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	12% 13% 4 9% 6% 4 5% 4 5% 6% 33%	2397
	11th to 20th	Day	14% 11% 5% 13% 6% 4 4 4 4 5% 31%	2520
	21st to end	Day	11% 11% 5% 12% 6% 6% 5% 4 6% 5% 29%	2772
February	1st to 10th	Day	12% 12% 4 10% 7% 7% 5% 5% 6% 6% 26%	1690
	11th to 20th	Day	12% 11% 4 12% 8% 5% 4 3 6% 6% 28%	1736
	21st to end	Day	13% 12% 4 9% 6% 5% 5% 4 6% 5% 32%	1570
March	1st to 10th	Day	19% 15% 4 8% 5% 4 4 4 4 5% 27%	3135
	11th to 20th	Day	15% 18% 5% 8% 5% 5% 5% 4 5% 6% 24%	3480
	21st to end	Day	23% 13% 3 7% 5% 4 4 3 4 6% 28%	3816
April	1st to 10th	Day	20% 12% 4 8% 5% 4 5% 4 5% 6% 26%	2270
	11th to 20th	Day	19% 9% 2 7% 5% 4 4 4 4 6% 34%	2437
	21st to end	Day	21% 11% 2 8% 4 4 5% 3 4 5% 32%	2470
May	1st to 10th	Day	16% 11% 3 8% 5% 5% 5% 4 5% 5% 31%	4106
	11th to 20th	Day	21% 8% 3 7% 5% 4 6% 4 5% 7% 29%	4160
	21st to end	Day	15% 8% 2 7% 6% 5% 6% 5% 7% 7% 31%	5150
June	1st to 10th	Day	23% 8% 3 7% 6% 5% 4 4 5% 7% 27%	2850
	11th to 20th	Day	18% 7% 2 6% 6% 5% 4 4 6% 8% 34%	2850
	21st to end	Day	25% 8% 3 6% 5% 5% 6% 4 6% 7% 25%	2850
July	1st to 10th	Day	14% 6% 2 7% 6% 6% 7% 5% 8% 9% 32%	4760
	11th to 20th	Day	15% 6% 3 7% 5% 5% 6% 4 5% 8% 37%	4450
	21st to end	Day	16% 6% 2 6% 5% 5% 6% 5% 6% 8% 35%	4814
August	1st to 10th	Day	17% 6% 2 7% 6% 6% 6% 5% 7% 7% 31%	4115
	11th to 20th	Day	14% 10% 3 7% 6% 5% 5% 5% 6% 8% 31%	4045
	21st to end	Day	14% 6% 2 6% 4 5% 5% 4 6% 8% 39%	4532
September	1st to 10th	Day	12% 5% 2 6% 4 5% 5% 4 5% 8% 44%	2214
	11th to 20th	Day	15% 5% 2 6% 3 3 4 4 5% 5% 47%	2090
	21st to end	Day	17% 7% 2 7% 4 4 4 4 5% 7% 40%	2090
October	1st to 10th	Day	17% 8% 3 7% 4 4 4 4 4 7% 38%	2025
	11th to 20th	Day	20% 9% 2 7% 5% 4 4 3 6% 6% 32%	1862
	21st to end	Day	22% 10% 3 8% 5% 4 4 4 5% 6% 29%	1881
November	1st to 10th	Day	18% 10% 2 7% 5% 5% 4 4 5% 6% 34%	1761
	11th to 20th	Day	17% 9% 3 8% 5% 4 4 4 5% 8% 34%	1685
	21st to end	Day	19% 11% 3 7% 5% 3 4 4 6% 7% 32%	1600
December	1st to 10th	Day	20% 12% 4 10% 6% 6% 3 3 4 6% 25%	1411
	11th to 20th	Day	22% 13% 4 6% 4 3 4 3 5% 5% 31%	1738
	21st to end	Day	20% 12% 4 7% 4 3 5% 4 5% 6% 31%	2452
January	1st to 10th	Night	11% 11% 5% 10% 8% 5% 5% 4 5% 6% 30%	4551
	11th to 20th	Night	12% 11% 4 10% 7% 6% 6% 5% 6% 7% 27%	4440
	21st to end	Night	11% 12% 4 9% 6% 6% 6% 4 7% 6% 28%	4884
February	1st to 10th	Night	11% 13% 4 8% 6% 6% 5% 4 7% 7% 30%	2489
	11th to 20th	Night	10% 11% 5% 10% 7% 6% 5% 3 6% 8% 29%	2327
	21st to end	Night	14% 10% 2 9% 5% 5% 5% 4 5% 6% 36%	1884
March	1st to 10th	Night	20% 13% 3 8% 5% 4 4 4 5% 5% 29%	3704
	11th to 20th	Night	15% 12% 4 9% 6% 6% 5% 5% 7% 7% 25%	3479
	21st to end	Night	25% 11% 3 7% 4 4 4 4 5% 8% 27%	3816
April	1st to 10th	Night	19% 12% 4 7% 5% 4 4 4 4 5% 32%	1908
	11th to 20th	Night	18% 10% 2 6% 3 4 4 3 5% 6% 39%	1693
	21st to end	Night	22% 10% 3 8% 4 4 4 3 5% 5% 31%	1710
May	1st to 10th	Night	22% 9% 3 6% 4 4 4 4 6% 7% 33%	2834
	11th to 20th	Night	20% 9% 3 9% 5% 6% 6% 5% 6% 7% 25%	2763
	21st to end	Night	15% 6% 2 5% 5% 5% 4 4 6% 9% 40%	2435
June	1st to 10th	Night	21% 9% 4 5% 5% 5% 5% 4 6% 6% 30%	1330
	11th to 20th	Night	14% 8% 2 7% 5% 5% 5% 4 6% 7% 37%	1330
	21st to end	Night	25% 8% 3 7% 5% 3 4 4 5% 6% 32%	1330
July	1st to 10th	Night	13% 6% 3 6% 5% 4 5% 4 7% 8% 40%	2210
	11th to 20th	Night	18% 6% 2 5% 4 4 4 4 5% 7% 40%	2506
	21st to end	Night	15% 7% 2 6% 4 4 4 4 6% 7% 40%	2739
August	1st to 10th	Night	20% 5% 2 7% 6% 6% 5% 4 6% 7% 32%	2781
	11th to 20th	Night	15% 7% 2 7% 4 5% 6% 5% 6% 8% 34%	2782
	21st to end	Night	13% 5% 2 7% 4 4 4 3 5% 6% 49%	3124
September	1st to 10th	Night	13% 4 2 5% 3 4 5% 3 5% 8% 48%	1963
	11th to 20th	Night	14% 7% 2 5% 3 4 3 3 5% 7% 49%	2090
	21st to end	Night	17% 7% 2 5% 4 4 3 3 4 7% 43%	2090
October	1st to 10th	Night	18% 5% 2 5% 4 4 4 3 6% 7% 42%	2154
	11th to 20th	Night	18% 7% 2 6% 5% 4 4 4 5% 7% 37%	2313
	21st to end	Night	22% 9% 2 6% 4 4 4 4 4 6% 33%	2717
November	1st to 10th	Night	18% 7% 3 6% 4 4 5% 4 7% 8% 35%	2537
	11th to 20th	Night	16% 7% 3 8% 4 4 4 4 6% 7% 37%	2712
	21st to end	Night	17% 10% 3 7% 4 4 4 4 6% 7% 33%	2800
December	1st to 10th	Night	19% 13% 4 7% 5% 5% 5% 4 4 6% 28%	2985
	11th to 20th	Night	22% 9% 3 6% 4 5% 5% 4 4 5% 32%	3681
	21st to end	Night	20% 11% 4 8% 5% 4 3 3 4 5% 34%	5288

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	50% 6% 17% 20% 6% 1	2398
	11th to 20th	Day	55% 4 9% 21% 9% 1	2520
	21st to end	Day	54% 7% 12% 14% 12% 1	2772
February	1st to 10th	Day	57% 6% 12% 14% 8% 2	1690
	11th to 20th	Day	56% 6% 13% 15% 11% 1	1744
	21st to end	Day	53% 6% 8% 19% 10% 3	1570
March	1st to 10th	Day	59% 5% 9% 12% 12% 3	3138
	11th to 20th	Day	59% 7% 13% 11% 9% 1	3480
	21st to end	Day	58% 4 7% 16% 13% 3	3816
April	1st to 10th	Day	57% 5% 10% 15% 10% 2	2270
	11th to 20th	Day	51% 5% 10% 20% 13% 2	2437
	21st to end	Day	53% 5% 9% 18% 11% 4	2470
May	1st to 10th	Day	50% 8% 11% 20% 9% 2	4120
	11th to 20th	Day	51% 7% 16% 18% 7% 1	4164
	21st to end	Day	46% 10% 13% 16% 14%	5150
June	1st to 10th	Day	55% 6% 13% 17% 9% 1	2850
	11th to 20th	Day	47% 6% 12% 21% 11% 2	2850
	21st to end	Day	56% 9% 12% 14% 8% 1	2850
July	1st to 10th	Day	44% 8% 17% 21% 10%	4685
	11th to 20th	Day	44% 7% 15% 28% 7%	4374
	21st to end	Day	44% 8% 13% 26% 8% 1	4661
August	1st to 10th	Day	48% 8% 15% 23% 6%	4101
	11th to 20th	Day	48% 7% 18% 21% 6%	4084
	21st to end	Day	41% 6% 16% 24% 13%	4532
September	1st to 10th	Day	38% 7% 14% 25% 15% 1	2214
	11th to 20th	Day	37% 5% 11% 29% 16% 1	2090
	21st to end	Day	42% 6% 11% 27% 13%	2090
October	1st to 10th	Day	52% 5% 12% 23% 7%	3363
	11th to 20th	Day	45% 4 12% 29% 10%	3078
	21st to end	Day	40% 5% 17% 20% 17% 1	3081
November	1st to 10th	Day	52% 5% 13% 19% 10% 1	1761
	11th to 20th	Day	50% 6% 13% 19% 10% 2	1685
	21st to end	Day	53% 7% 17% 18% 5%	1600
December	1st to 10th	Day	61% 5% 12% 14% 7%	1411
	11th to 20th	Day	54% 6% 11% 16% 12% 1	1738
	21st to end	Day	54% 6% 13% 16% 8% 3	2452
January	1st to 10th	Night	53% 9% 17% 16% 5%	4551
	11th to 20th	Night	55% 7% 14% 18% 5% 1	4440
	21st to end	Night	53% 7% 11% 17% 10% 1	4884
February	1st to 10th	Night	53% 6% 13% 18% 9% 2	2489
	11th to 20th	Night	53% 6% 13% 17% 10% 1	2330
	21st to end	Night	50% 6% 10% 20% 12% 2	1884
March	1st to 10th	Night	59% 5% 9% 18% 8% 2	3714
	11th to 20th	Night	55% 9% 14% 12% 8% 1	3480
	21st to end	Night	55% 5% 8% 19% 10% 2	3816
April	1st to 10th	Night	54% 6% 8% 15% 14% 3	1908
	11th to 20th	Night	47% 5% 10% 20% 15% 2	1693
	21st to end	Night	55% 4 9% 16% 13% 3	1710
May	1st to 10th	Night	47% 8% 15% 20% 9% 1	2840
	11th to 20th	Night	52% 11% 14% 16% 6% 1	2764
	21st to end	Night	39% 10% 17% 21% 12% 1	2436
June	1st to 10th	Night	52% 7% 12% 20% 8%	1330
	11th to 20th	Night	45% 8% 13% 21% 12% 1	1330
	21st to end	Night	53% 7% 14% 17% 8% 1	1330
July	1st to 10th	Night	39% 7% 21% 23% 11%	2175
	11th to 20th	Night	43% 5% 15% 29% 8%	2459
	21st to end	Night	43% 7% 16% 26% 9%	2651
August	1st to 10th	Night	50% 7% 16% 23% 5%	2771
	11th to 20th	Night	45% 8% 18% 21% 7% 1	2809
	21st to end	Night	37% 6% 14% 26% 16% 1	3124
September	1st to 10th	Night	33% 8% 15% 30% 13% 1	1963
	11th to 20th	Night	35% 6% 14% 30% 14% 1	2090
	21st to end	Night	40% 6% 13% 25% 15% 1	2090
October	1st to 10th	Night	45% 6% 12% 26% 11%	3596
	11th to 20th	Night	39% 5% 14% 30% 12%	3836
	21st to end	Night	40% 4 19% 21% 13% 2	4467
November	1st to 10th	Night	46% 8% 15% 22% 9% 1	2537
	11th to 20th	Night	47% 6% 15% 20% 11% 2	2712
	21st to end	Night	50% 8% 15% 19% 8%	2800
December	1st to 10th	Night	57% 7% 13% 18% 5%	2985
	11th to 20th	Night	54% 6% 11% 17% 12%	3682
	21st to end	Night	53% 5% 13% 18% 9% 2	5288

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	24% 23% 33% 16% 3	180
	11th to 20th	Day	30% 25% 33% 8% 3 1	180
	21st to end	Day	21% 22% 37% 13% 8%	198
February	1st to 10th	Day	25% 21% 35% 16% 3 1	350
	11th to 20th	Day	25% 27% 31% 14% 2	401
	21st to end	Day	24% 27% 30% 17% 2	382
March	1st to 10th	Day	27% 25% 32% 14% 2	460
	11th to 20th	Day	25% 23% 30% 17% 4	460
	21st to end	Day	29% 22% 26% 17% 5% 1	506
April	1st to 10th	Day	34% 21% 26% 14% 3 1	460
	11th to 20th	Day	31% 23% 28% 12% 5% 1	452
	21st to end	Day	32% 22% 28% 12% 4 1	460
May	1st to 10th	Day	30% 18% 32% 14% 4 1	463
	11th to 20th	Day	26% 21% 29% 18% 5% 1	487
	21st to end	Day	23% 20% 32% 19% 5% 1	712
June	1st to 10th	Day	28% 17% 30% 17% 7% 1	680
	11th to 20th	Day	23% 14% 29% 23% 11% 1	680
	21st to end	Day	28% 11% 29% 22% 9% 1	680
July	1st to 10th	Day	17% 13% 34% 24% 11% 1	670
	11th to 20th	Day	19% 9% 41% 20% 9% 2	493
	21st to end	Day	18% 10% 33% 29% 9% 2	532
August	1st to 10th	Day	19% 10% 32% 27% 10% 2	486
	11th to 20th	Day	19% 10% 29% 28% 12% 3	479
	21st to end	Day	19% 13% 25% 29% 12% 3	539
September	1st to 10th	Day	14% 16% 29% 25% 13% 3	490
	11th to 20th	Day	19% 13% 26% 24% 12% 6%	490
	21st to end	Day	22% 13% 30% 19% 11% 5%	490
October	1st to 10th	Day	20% 15% 29% 21% 11% 4	455
	11th to 20th	Day	28% 17% 28% 17% 7% 3	390
	21st to end	Day	32% 18% 25% 20% 4	429
November	1st to 10th	Day	30% 15% 29% 19% 6%	395
	11th to 20th	Day	27% 21% 32% 15% 5% 1	400
	21st to end	Day	31% 21% 27% 18% 3 1	400
December	1st to 10th	Day	24% 18% 35% 19% 4	211
	11th to 20th	Day	35% 23% 28% 11% 3 1	200
	21st to end	Day	31% 26% 27% 12% 3	204
January	1st to 10th	Night	19% 23% 35% 19% 3	793
	11th to 20th	Night	24% 20% 34% 18% 4	760
	21st to end	Night	15% 21% 38% 22% 4	836
February	1st to 10th	Night	20% 22% 35% 20% 3	760
	11th to 20th	Night	21% 24% 36% 16% 3	743
	21st to end	Night	23% 18% 33% 23% 3	628
March	1st to 10th	Night	23% 18% 38% 19% 2	760
	11th to 20th	Night	23% 18% 32% 20% 6%	760
	21st to end	Night	23% 18% 33% 20% 6%	836
April	1st to 10th	Night	29% 16% 33% 18% 4	760
	11th to 20th	Night	24% 16% 33% 20% 6%	569
	21st to end	Night	33% 14% 29% 19% 5%	570
May	1st to 10th	Night	27% 13% 31% 25% 4 1	570
	11th to 20th	Night	25% 13% 33% 23% 7%	538
	21st to end	Night	19% 9% 38% 26% 6%	411
June	1st to 10th	Night	26% 9% 30% 28% 7%	380
	11th to 20th	Night	17% 9% 29% 33% 11%	380
	21st to end	Night	28% 6% 24% 34% 7%	380
July	1st to 10th	Night	19% 6% 31% 34% 11%	370
	11th to 20th	Night	19% 3 27% 38% 12%	368
	21st to end	Night	20% 5% 25% 38% 13%	416
August	1st to 10th	Night	20% 5% 24% 36% 15%	536
	11th to 20th	Night	16% 6% 24% 37% 16% 1	562
	21st to end	Night	15% 8% 27% 34% 15% 1	627
September	1st to 10th	Night	14% 7% 34% 30% 14% 1	738
	11th to 20th	Night	17% 11% 24% 32% 14% 2	760
	21st to end	Night	21% 9% 30% 26% 14% 1	760
October	1st to 10th	Night	22% 10% 26% 29% 12% 1	760
	11th to 20th	Night	24% 11% 30% 24% 10% 1	760
	21st to end	Night	28% 18% 28% 22% 4	836
November	1st to 10th	Night	26% 13% 32% 23% 7%	780
	11th to 20th	Night	23% 19% 29% 21% 7% 1	857
	21st to end	Night	26% 21% 26% 21% 5%	900
December	1st to 10th	Night	27% 15% 34% 20% 3 1	900
	11th to 20th	Night	27% 20% 31% 19% 3	900
	21st to end	Night	27% 18% 33% 18% 3	953

Page generated at 2024-12-21 04:13:48. Version ac07

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