Kennelly's Mountain
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kennelly's Mountain clear sky chart from 2005-11-06 to 2025-04-11.

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	15% 11% 4 9% 5% 5% 5% 4 5% 6% 31%	113589
	Night	15% 12% 4 10% 6% 5% 4 3 5% 6% 30%	114662
Transparency	Day	51% 7% 12% 19% 10% 1	117141
	Night	53% 7% 12% 18% 9% 1	119274
Seeing	Day	23% 18% 31% 18% 7% 2	14874
	Night	22% 16% 31% 23% 8% 1	24196

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% 15% 7% 13% 10% 8% 5% 4 5% 4 18%	3597
	11th to 20th	Day	11% 15% 7% 16% 9% 5% 5% 4 4 4 20%	3570
	21st to end	Day	12% 20% 6% 16% 6% 5% 4 2 4 5% 20%	4282
February	1st to 10th	Day	12% 16% 6% 13% 8% 6% 5% 4 5% 5% 21%	1800
	11th to 20th	Day	11% 15% 5% 12% 7% 6% 5% 3 5% 6% 26%	1753
	21st to end	Day	16% 15% 4 10% 6% 6% 5% 4 5% 4 24%	1605
March	1st to 10th	Day	17% 14% 5% 12% 5% 4 4 3 4 6% 26%	4631
	11th to 20th	Day	10% 13% 5% 11% 6% 5% 5% 4 6% 6% 28%	4980
	21st to end	Day	14% 13% 4 9% 5% 4 3 3 4 4 38%	5665
April	1st to 10th	Day	20% 14% 4 7% 4 5% 4 3 5% 6% 30%	2400
	11th to 20th	Day	22% 11% 3 6% 4 3 3 3 3 4 37%	2254
	21st to end	Day	21% 11% 4 8% 4 4 4 3 4 5% 33%	2424
May	1st to 10th	Day	19% 9% 4 8% 5% 5% 5% 3 5% 7% 32%	4421
	11th to 20th	Day	15% 9% 3 8% 5% 5% 5% 4 6% 8% 32%	4398
	21st to end	Day	14% 8% 2 7% 5% 4 5% 4 6% 7% 39%	4837
June	1st to 10th	Day	21% 9% 3 7% 5% 4 5% 4 5% 6% 30%	2660
	11th to 20th	Day	15% 6% 3 6% 4 5% 5% 4 6% 8% 37%	2660
	21st to end	Day	17% 8% 3 6% 6% 5% 4 4 6% 8% 33%	2660
July	1st to 10th	Day	12% 7% 3 7% 6% 5% 6% 4 7% 8% 34%	4440
	11th to 20th	Day	13% 5% 2 6% 5% 5% 6% 4 7% 9% 39%	4440
	21st to end	Day	10% 6% 2 6% 5% 4 5% 4 6% 8% 45%	4814
August	1st to 10th	Day	16% 7% 3 8% 5% 5% 5% 4 5% 7% 35%	4233
	11th to 20th	Day	18% 6% 2 6% 5% 4 5% 4 6% 7% 36%	4044
	21st to end	Day	11% 6% 2 6% 4 5% 5% 5% 7% 9% 41%	4212
September	1st to 10th	Day	15% 6% 3 6% 4 4 5% 4 5% 7% 40%	2280
	11th to 20th	Day	13% 6% 2 5% 4 4 4 3 5% 7% 46%	2280
	21st to end	Day	17% 8% 2 6% 5% 4 4 3 5% 7% 38%	2004
October	1st to 10th	Day	20% 10% 3 7% 4 4 5% 3 5% 6% 34%	1900
	11th to 20th	Day	20% 12% 4 9% 4 4 5% 4 5% 6% 28%	1900
	21st to end	Day	25% 12% 3 9% 5% 5% 5% 3 5% 5% 24%	1990
November	1st to 10th	Day	14% 12% 3 7% 5% 5% 5% 4 4 7% 34%	1709
	11th to 20th	Day	15% 13% 6% 10% 6% 5% 4 4 5% 5% 28%	1600
	21st to end	Day	19% 16% 6% 10% 6% 6% 4 3 4 5% 19%	1600
December	1st to 10th	Day	19% 22% 6% 13% 7% 5% 5% 3 4 5% 11%	2600
	11th to 20th	Day	16% 18% 6% 13% 6% 4 4 3 3 3 24%	2986
	21st to end	Day	21% 18% 6% 15% 5% 4 3 3 3 4 19%	3960
January	1st to 10th	Night	13% 16% 9% 16% 8% 5% 4 3 4 5% 18%	6349
	11th to 20th	Night	10% 13% 6% 15% 9% 8% 6% 4 5% 5% 20%	6315
	21st to end	Night	12% 17% 7% 14% 7% 7% 5% 3 4 4 20%	6657
February	1st to 10th	Night	11% 15% 6% 12% 7% 6% 5% 4 5% 6% 23%	2600
	11th to 20th	Night	12% 13% 6% 11% 6% 6% 4 3 4 6% 28%	2533
	21st to end	Night	13% 12% 5% 9% 7% 6% 5% 3 7% 6% 27%	2025
March	1st to 10th	Night	19% 15% 5% 10% 5% 5% 4 3 3 3 28%	5194
	11th to 20th	Night	9% 12% 4 9% 6% 5% 6% 5% 7% 8% 28%	4979
	21st to end	Night	15% 12% 3 9% 6% 5% 4 3 4 6% 31%	5266
April	1st to 10th	Night	19% 12% 3 8% 5% 4 4 3 4 5% 32%	2000
	11th to 20th	Night	18% 10% 2 7% 4 6% 3 3 4 6% 37%	1882
	21st to end	Night	20% 10% 4 8% 5% 4 4 3 5% 6% 33%	1772
May	1st to 10th	Night	19% 10% 3 6% 5% 5% 4 4 5% 7% 33%	2519
	11th to 20th	Night	17% 8% 3 6% 4 5% 5% 4 5% 7% 36%	2495
	21st to end	Night	11% 7% 3 7% 5% 4 5% 3 7% 8% 40%	2738
June	1st to 10th	Night	16% 7% 3 7% 5% 4 5% 4 7% 7% 35%	1520
	11th to 20th	Night	13% 8% 2 6% 4 4 5% 3 6% 6% 43%	1520
	21st to end	Night	18% 6% 2 6% 4 4 4 3 5% 8% 37%	1520
July	1st to 10th	Night	10% 8% 3 7% 6% 5% 6% 5% 6% 7% 37%	2520
	11th to 20th	Night	12% 5% 2 6% 5% 4 5% 3 6% 7% 45%	2520
	21st to end	Night	10% 6% 2 6% 4 4 4 4 7% 7% 47%	2739
August	1st to 10th	Night	12% 5% 2 6% 4 5% 5% 4 6% 8% 42%	2692
	11th to 20th	Night	15% 5% 2 6% 4 5% 4 3 5% 7% 44%	2785
	21st to end	Night	12% 6% 2 5% 4 5% 4 4 5% 8% 45%	3411
September	1st to 10th	Night	11% 6% 2 5% 4 4 5% 4 5% 7% 47%	1900
	11th to 20th	Night	14% 5% 1 4 3 4 4 3 4 6% 51%	1900
	21st to end	Night	16% 7% 2 5% 4 4 4 3 5% 7% 42%	2172
October	1st to 10th	Night	19% 8% 3 6% 4 4 4 3 5% 6% 39%	2280
	11th to 20th	Night	19% 11% 3 8% 5% 5% 4 4 5% 5% 31%	2280
	21st to end	Night	21% 12% 3 8% 5% 5% 5% 3 5% 6% 26%	2608
November	1st to 10th	Night	15% 13% 3 7% 5% 4 4 3 5% 5% 35%	2587
	11th to 20th	Night	16% 13% 4 9% 6% 5% 5% 4 5% 6% 28%	2800
	21st to end	Night	19% 17% 5% 11% 5% 4 4 3 5% 6% 22%	2800
December	1st to 10th	Night	17% 18% 5% 13% 6% 5% 5% 4 5% 5% 16%	4580
	11th to 20th	Night	19% 16% 6% 12% 6% 4 3 2 4 4 24%	5208
	21st to end	Night	23% 18% 5% 13% 6% 4 3 2 3 3 20%	6996

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	66% 8% 9% 10% 7%	3598
	11th to 20th	Day	66% 7% 10% 9% 8% 1	3600
	21st to end	Day	68% 5% 7% 11% 8% 1	4282
February	1st to 10th	Day	63% 7% 9% 14% 6% 1	1800
	11th to 20th	Day	58% 6% 12% 14% 9% 1	1762
	21st to end	Day	60% 7% 10% 12% 9% 2	1605
March	1st to 10th	Day	60% 5% 9% 11% 14% 2	4634
	11th to 20th	Day	52% 7% 15% 15% 9% 2	4980
	21st to end	Day	49% 5% 7% 19% 17% 3	5665
April	1st to 10th	Day	54% 6% 8% 17% 12% 3	2400
	11th to 20th	Day	50% 6% 7% 20% 15% 2	2254
	21st to end	Day	53% 6% 8% 15% 14% 4	2424
May	1st to 10th	Day	48% 9% 11% 19% 11% 2	4435
	11th to 20th	Day	45% 12% 14% 18% 10% 1	4402
	21st to end	Day	41% 9% 13% 19% 15% 2	4837
June	1st to 10th	Day	52% 8% 11% 17% 11% 1	2660
	11th to 20th	Day	42% 8% 12% 22% 13% 2	2660
	21st to end	Day	47% 9% 11% 20% 11% 1	2660
July	1st to 10th	Day	44% 7% 15% 23% 11% 1	4370
	11th to 20th	Day	38% 9% 15% 28% 10%	4365
	21st to end	Day	36% 8% 12% 32% 12%	4661
August	1st to 10th	Day	47% 7% 14% 22% 10%	4219
	11th to 20th	Day	44% 7% 16% 25% 7% 1	4083
	21st to end	Day	37% 8% 15% 30% 10% 1	4212
September	1st to 10th	Day	40% 8% 14% 26% 11%	2280
	11th to 20th	Day	36% 9% 13% 28% 15%	2280
	21st to end	Day	46% 7% 14% 23% 10%	2004
October	1st to 10th	Day	49% 5% 10% 28% 7%	3160
	11th to 20th	Day	47% 6% 13% 22% 11% 1	3140
	21st to end	Day	53% 6% 17% 18% 6%	3254
November	1st to 10th	Day	49% 8% 15% 21% 6% 1	1709
	11th to 20th	Day	57% 6% 13% 14% 9% 1	1600
	21st to end	Day	67% 8% 10% 9% 5% 1	1600
December	1st to 10th	Day	74% 6% 10% 7% 2	2600
	11th to 20th	Day	65% 6% 9% 13% 7%	2986
	21st to end	Day	70% 4 8% 14% 5%	3960
January	1st to 10th	Night	68% 7% 10% 11% 4	6349
	11th to 20th	Night	63% 8% 12% 11% 6%	6360
	21st to end	Night	66% 6% 7% 8% 11% 1	6657
February	1st to 10th	Night	60% 7% 10% 15% 6% 1	2600
	11th to 20th	Night	57% 6% 10% 18% 7% 1	2535
	21st to end	Night	55% 8% 10% 18% 9% 1	2025
March	1st to 10th	Night	60% 5% 7% 15% 9% 4	5204
	11th to 20th	Night	49% 10% 18% 15% 7% 2	4980
	21st to end	Night	50% 6% 10% 20% 12% 2	5266
April	1st to 10th	Night	53% 6% 9% 18% 12% 2	2000
	11th to 20th	Night	48% 6% 8% 22% 14% 2	1882
	21st to end	Night	51% 6% 9% 16% 16% 2	1772
May	1st to 10th	Night	47% 10% 11% 20% 10% 2	2525
	11th to 20th	Night	41% 13% 14% 21% 9% 1	2496
	21st to end	Night	37% 11% 14% 20% 17% 1	2739
June	1st to 10th	Night	44% 10% 13% 22% 10% 1	1520
	11th to 20th	Night	38% 8% 11% 24% 16% 2	1520
	21st to end	Night	44% 8% 16% 19% 13% 1	1520
July	1st to 10th	Night	42% 9% 15% 18% 14% 1	2480
	11th to 20th	Night	37% 6% 13% 33% 10%	2472
	21st to end	Night	35% 9% 15% 28% 14%	2651
August	1st to 10th	Night	38% 8% 15% 26% 12% 2	2682
	11th to 20th	Night	38% 7% 16% 30% 8% 1	2812
	21st to end	Night	36% 7% 16% 29% 10% 2	3411
September	1st to 10th	Night	34% 9% 15% 27% 14% 1	1900
	11th to 20th	Night	34% 6% 14% 33% 11% 1	1900
	21st to end	Night	41% 7% 13% 29% 10%	2172
October	1st to 10th	Night	39% 6% 12% 29% 14%	3800
	11th to 20th	Night	45% 7% 16% 21% 10%	3779
	21st to end	Night	50% 7% 16% 20% 7%	4294
November	1st to 10th	Night	50% 7% 14% 20% 9%	2587
	11th to 20th	Night	56% 7% 11% 17% 8% 1	2800
	21st to end	Night	62% 8% 12% 15% 4	2800
December	1st to 10th	Night	68% 8% 13% 9% 2	4580
	11th to 20th	Night	64% 5% 8% 12% 10% 1	5208
	21st to end	Night	70% 5% 6% 11% 9%	6996

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% 22% 40% 12% 4 1	200
	11th to 20th	Day	28% 21% 38% 10% 4 1	200
	21st to end	Day	23% 25% 36% 11% 4 1	290
February	1st to 10th	Day	31% 27% 31% 8% 3	300
	11th to 20th	Day	32% 26% 38% 3 1	300
	21st to end	Day	33% 26% 32% 8% 1	369
March	1st to 10th	Day	27% 24% 35% 12% 3	500
	11th to 20th	Day	28% 21% 33% 15% 3 1	500
	21st to end	Day	31% 23% 28% 12% 5%	550
April	1st to 10th	Day	32% 22% 29% 11% 5%	500
	11th to 20th	Day	34% 23% 18% 16% 7% 1	452
	21st to end	Day	33% 18% 31% 11% 6% 1	460
May	1st to 10th	Day	25% 19% 31% 17% 6% 2	463
	11th to 20th	Day	20% 18% 32% 21% 7% 2	487
	21st to end	Day	18% 18% 34% 20% 7% 4	529
June	1st to 10th	Day	24% 14% 35% 20% 7%	490
	11th to 20th	Day	17% 16% 32% 22% 12% 2	490
	21st to end	Day	20% 16% 34% 19% 10% 2	490
July	1st to 10th	Day	11% 9% 34% 34% 9% 3	485
	11th to 20th	Day	14% 12% 33% 28% 11% 3	484
	21st to end	Day	14% 9% 36% 27% 11% 3	532
August	1st to 10th	Day	16% 7% 33% 28% 12% 5%	486
	11th to 20th	Day	13% 10% 29% 28% 14% 5%	479
	21st to end	Day	14% 14% 31% 25% 11% 6%	539
September	1st to 10th	Day	16% 13% 31% 21% 13% 7%	490
	11th to 20th	Day	12% 12% 25% 24% 16% 11%	490
	21st to end	Day	18% 16% 28% 20% 13% 6%	490
October	1st to 10th	Day	24% 19% 23% 20% 9% 4	490
	11th to 20th	Day	27% 23% 31% 13% 5% 2	490
	21st to end	Day	30% 19% 31% 16% 4	486
November	1st to 10th	Day	28% 20% 30% 16% 6% 1	343
	11th to 20th	Day	27% 24% 32% 10% 6% 2	200
	21st to end	Day	34% 23% 34% 7% 3 1	200
December	1st to 10th	Day	32% 17% 36% 14% 2	200
	11th to 20th	Day	32% 31% 27% 8% 3 1	200
	21st to end	Day	30% 25% 29% 12% 4	220
January	1st to 10th	Night	25% 23% 34% 15% 3	800
	11th to 20th	Night	26% 22% 29% 18% 5% 1	800
	21st to end	Night	18% 17% 38% 21% 4	880
February	1st to 10th	Night	21% 21% 37% 19% 2	800
	11th to 20th	Night	21% 22% 41% 13% 3	783
	21st to end	Night	22% 22% 32% 20% 3	660
March	1st to 10th	Night	26% 19% 34% 18% 3	800
	11th to 20th	Night	24% 22% 31% 18% 4 1	800
	21st to end	Night	25% 16% 32% 20% 6%	880
April	1st to 10th	Night	28% 17% 31% 20% 4	800
	11th to 20th	Night	23% 22% 30% 18% 6%	754
	21st to end	Night	24% 16% 28% 24% 8%	632
May	1st to 10th	Night	23% 11% 28% 28% 9% 1	385
	11th to 20th	Night	21% 10% 33% 27% 8%	374
	21st to end	Night	13% 11% 36% 29% 10%	411
June	1st to 10th	Night	16% 9% 36% 32% 7%	380
	11th to 20th	Night	15% 12% 33% 29% 10% 1	380
	21st to end	Night	21% 9% 29% 28% 13%	380
July	1st to 10th	Night	7% 10% 33% 37% 12% 1	370
	11th to 20th	Night	11% 8% 29% 40% 12%	368
	21st to end	Night	9% 5% 32% 41% 13%	416
August	1st to 10th	Night	11% 6% 25% 41% 17%	486
	11th to 20th	Night	12% 4 25% 38% 20% 2	564
	21st to end	Night	13% 9% 30% 30% 16% 2	797
September	1st to 10th	Night	14% 8% 32% 29% 15% 1	760
	11th to 20th	Night	17% 7% 23% 30% 19% 4	760
	21st to end	Night	20% 12% 22% 25% 18% 2	760
October	1st to 10th	Night	22% 14% 27% 24% 12% 2	760
	11th to 20th	Night	26% 15% 32% 19% 8% 1	760
	21st to end	Night	28% 17% 29% 20% 5%	836
November	1st to 10th	Night	25% 17% 30% 22% 4 1	780
	11th to 20th	Night	22% 22% 32% 15% 8% 1	800
	21st to end	Night	31% 19% 27% 18% 4	800
December	1st to 10th	Night	29% 20% 32% 16% 3	800
	11th to 20th	Night	27% 22% 29% 19% 2 1	800
	21st to end	Night	32% 18% 32% 15% 4	880

Page generated at 2025-04-08 09:17:25. Version ac07

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