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 2024-07-31.

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 5% 7% 32%	89636
	Night	17% 9% 3 7% 5% 5% 5% 4 5% 7% 34%	90233
Transparency	Day	51% 7% 13% 19% 10% 1	89348
	Night	49% 7% 13% 20% 9% 1	90076
Seeing	Day	25% 18% 30% 19% 7% 1	15462
	Night	23% 15% 31% 24% 7%	23628

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	15% 6% 2 7% 6% 5% 5% 4 7% 9% 34%	2850
	11th to 20th	Day	16% 6% 3 7% 6% 6% 5% 4 5% 8% 34%	2670
	21st to end	Day	14% 7% 2 7% 6% 5% 7% 6% 7% 8% 32%	2887
August	1st to 10th	Day	18% 6% 2 6% 5% 5% 6% 5% 8% 8% 32%	2337
	11th to 20th	Day	14% 7% 2 7% 7% 6% 5% 5% 6% 9% 34%	2304
	21st to end	Day	14% 6% 2 7% 4 5% 5% 4 6% 8% 39%	2574
September	1st to 10th	Day	12% 5% 2 6% 4 5% 5% 4 5% 8% 43%	2098
	11th to 20th	Day	15% 6% 2 6% 3 3 4 3 5% 5% 47%	1980
	21st to end	Day	17% 7% 2 7% 4 4 3 4 5% 7% 41%	1980
October	1st to 10th	Day	17% 8% 3 7% 4 4 4 3 4 7% 39%	1919
	11th to 20th	Day	20% 10% 3 7% 5% 4 4 4 6% 6% 32%	1764
	21st to end	Day	23% 10% 3 8% 5% 4 4 4 5% 6% 27%	1782
November	1st to 10th	Day	18% 10% 2 7% 5% 5% 4 4 5% 5% 34%	1671
	11th to 20th	Day	18% 8% 3 8% 5% 4 4 4 5% 8% 34%	1601
	21st to end	Day	19% 10% 2 7% 5% 3 4 4 6% 7% 33%	1520
December	1st to 10th	Day	20% 12% 4 10% 6% 6% 3 4 4 6% 25%	1341
	11th to 20th	Day	22% 13% 4 6% 4 3 4 4 5% 5% 31%	1668
	21st to end	Day	20% 12% 4 7% 4 3 5% 4 5% 6% 31%	2431
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	17% 6% 3 5% 5% 4 5% 4 6% 8% 39%	1330
	11th to 20th	Night	16% 7% 2 5% 3 4 4 3 7% 9% 40%	1506
	21st to end	Night	15% 8% 2 6% 4 4 4 4 6% 7% 39%	1662
August	1st to 10th	Night	17% 5% 3 5% 3 4 4 4 5% 7% 42%	1581
	11th to 20th	Night	14% 5% 2 6% 4 5% 5% 4 6% 8% 40%	1596
	21st to end	Night	13% 6% 2 6% 3 3 3 3 5% 7% 49%	1782
September	1st to 10th	Night	13% 4 2 5% 3 4 5% 3 5% 8% 48%	1859
	11th to 20th	Night	14% 7% 2 5% 3 4 3 3 5% 7% 48%	1980
	21st to end	Night	17% 6% 2 5% 4 3 3 3 4 7% 44%	1980
October	1st to 10th	Night	17% 5% 3 5% 4 4 4 3 6% 7% 43%	2040
	11th to 20th	Night	19% 7% 2 6% 5% 5% 4 4 5% 7% 37%	2191
	21st to end	Night	23% 9% 2 6% 4 4 4 4 4 6% 32%	2574
November	1st to 10th	Night	18% 7% 3 6% 4 4 5% 4 6% 8% 35%	2407
	11th to 20th	Night	17% 7% 3 8% 4 4 4 4 5% 7% 37%	2576
	21st to end	Night	17% 9% 3 7% 5% 4 4 4 6% 7% 33%	2660
December	1st to 10th	Night	20% 13% 3 7% 5% 5% 5% 4 4 6% 28%	2835
	11th to 20th	Night	22% 8% 3 6% 5% 5% 5% 4 4 5% 32%	3531
	21st to end	Night	20% 10% 4 8% 5% 4 3 3 4 5% 34%	5236

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% 9% 15% 22% 10% 1	2775
	11th to 20th	Day	45% 8% 14% 23% 9% 1	2594
	21st to end	Day	46% 9% 14% 22% 9% 1	2734
August	1st to 10th	Day	44% 9% 17% 23% 6%	2323
	11th to 20th	Day	44% 9% 16% 22% 8%	2304
	21st to end	Day	41% 7% 15% 24% 12%	2574
September	1st to 10th	Day	39% 7% 14% 25% 14% 1	2098
	11th to 20th	Day	38% 5% 11% 28% 16% 1	1980
	21st to end	Day	41% 6% 12% 27% 14%	1980
October	1st to 10th	Day	44% 7% 12% 26% 11%	1919
	11th to 20th	Day	51% 6% 15% 22% 7%	1764
	21st to end	Day	57% 7% 12% 15% 9% 1	1782
November	1st to 10th	Day	53% 5% 14% 18% 10% 1	1671
	11th to 20th	Day	51% 6% 13% 19% 10% 1	1601
	21st to end	Day	52% 7% 18% 18% 5%	1520
December	1st to 10th	Day	61% 5% 12% 15% 6% 1	1341
	11th to 20th	Day	55% 6% 11% 16% 12% 1	1668
	21st to end	Day	54% 6% 13% 16% 8% 3	2431
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	41% 9% 19% 22% 10%	1295
	11th to 20th	Night	40% 8% 16% 26% 10%	1459
	21st to end	Night	44% 7% 16% 21% 11% 1	1574
August	1st to 10th	Night	40% 9% 18% 28% 6%	1571
	11th to 20th	Night	40% 10% 17% 26% 7%	1596
	21st to end	Night	34% 7% 16% 29% 13% 1	1782
September	1st to 10th	Night	33% 8% 16% 29% 12% 1	1859
	11th to 20th	Night	36% 6% 13% 29% 14% 1	1980
	21st to end	Night	39% 7% 13% 25% 15% 1	1980
October	1st to 10th	Night	40% 7% 10% 28% 13%	2040
	11th to 20th	Night	47% 6% 14% 24% 8%	2191
	21st to end	Night	53% 6% 12% 19% 9%	2574
November	1st to 10th	Night	46% 8% 15% 21% 9% 1	2407
	11th to 20th	Night	48% 6% 14% 20% 11% 1	2576
	21st to end	Night	49% 8% 16% 19% 8%	2660
December	1st to 10th	Night	58% 7% 13% 18% 5%	2835
	11th to 20th	Night	54% 6% 12% 17% 11%	3532
	21st to end	Night	53% 5% 13% 18% 9% 2	5236

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% 9% 34% 29% 9% 2	529
August	1st to 10th	Day	19% 9% 31% 28% 10% 2	446
	11th to 20th	Day	18% 10% 27% 29% 13% 3	439
	21st to end	Day	19% 13% 25% 29% 12% 3	495
September	1st to 10th	Day	14% 15% 28% 26% 13% 3	450
	11th to 20th	Day	21% 14% 27% 21% 12% 6%	450
	21st to end	Day	21% 14% 31% 18% 11% 5%	450
October	1st to 10th	Day	19% 15% 29% 22% 10% 4	419
	11th to 20th	Day	28% 18% 28% 17% 7% 3	360
	21st to end	Day	33% 17% 26% 19% 5%	396
November	1st to 10th	Day	30% 15% 28% 20% 6%	365
	11th to 20th	Day	28% 18% 32% 15% 6% 1	370
	21st to end	Day	29% 21% 28% 18% 4 1	370
December	1st to 10th	Day	25% 19% 35% 19% 3 1	191
	11th to 20th	Day	33% 24% 29% 9% 3 1	180
	21st to end	Day	32% 26% 26% 13% 3	198
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	19% 5% 25% 38% 13%	416
August	1st to 10th	Night	19% 5% 24% 36% 15%	507
	11th to 20th	Night	16% 6% 24% 37% 17% 1	532
	21st to end	Night	15% 7% 27% 35% 14% 1	594
September	1st to 10th	Night	14% 7% 34% 29% 14% 1	699
	11th to 20th	Night	18% 11% 25% 31% 13% 2	720
	21st to end	Night	21% 9% 31% 25% 13% 1	720
October	1st to 10th	Night	22% 10% 27% 29% 11% 1	720
	11th to 20th	Night	24% 11% 30% 24% 10% 1	720
	21st to end	Night	29% 17% 28% 22% 4	792
November	1st to 10th	Night	26% 13% 32% 23% 7%	740
	11th to 20th	Night	23% 17% 29% 21% 7% 1	811
	21st to end	Night	25% 22% 27% 22% 5%	850
December	1st to 10th	Night	28% 15% 34% 19% 3 1	850
	11th to 20th	Night	26% 20% 31% 19% 3	850
	21st to end	Night	28% 19% 33% 18% 3	935

Page generated at 2024-07-28 09:52:14. Version ac07

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