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 2026-08-30.

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% 10% 4 9% 5% 5% 5% 4 5% 6% 32%	144675
	Night	15% 12% 4 9% 6% 5% 5% 4 5% 6% 31%	137513
Transparency	Day	50% 7% 12% 20% 10% 1	148181
	Night	52% 7% 12% 19% 10% 1	142096
Seeing	Day	23% 18% 32% 18% 7% 2	16701
	Night	22% 16% 31% 23% 8% 1	25784

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% 16% 6% 13% 10% 7% 6% 4 5% 5% 18%	4661
	11th to 20th	Day	10% 18% 8% 16% 8% 5% 4 4 4 4 17%	4650
	21st to end	Day	10% 17% 6% 18% 8% 7% 5% 3 4 4 19%	5541
February	1st to 10th	Day	12% 15% 6% 13% 8% 6% 5% 4 5% 4 22%	1890
	11th to 20th	Day	11% 15% 5% 12% 7% 5% 5% 4 5% 6% 25%	1843
	21st to end	Day	16% 15% 4 10% 6% 6% 5% 4 5% 4 24%	1683
March	1st to 10th	Day	17% 14% 5% 12% 5% 4 4 3 4 6% 26%	4734
	11th to 20th	Day	10% 13% 5% 11% 6% 5% 5% 4 6% 6% 28%	5090
	21st to end	Day	14% 13% 4 9% 5% 4 3 3 4 4 37%	5790
April	1st to 10th	Day	20% 14% 4 7% 4 5% 4 3 5% 5% 30%	2520
	11th to 20th	Day	21% 12% 3 7% 4 3 3 3 3 4 36%	2494
	21st to end	Day	21% 11% 4 7% 4 4 4 3 4 5% 33%	2680
May	1st to 10th	Day	19% 10% 3 8% 5% 4 5% 4 5% 6% 30%	8232
	11th to 20th	Day	15% 9% 3 8% 5% 5% 5% 4 6% 8% 33%	8221
	21st to end	Day	19% 9% 3 7% 5% 4 4 3 5% 6% 36%	9060
June	1st to 10th	Day	21% 8% 3 7% 5% 4 5% 4 5% 6% 31%	2940
	11th to 20th	Day	15% 6% 3 6% 5% 5% 5% 4 6% 8% 36%	2940
	21st to end	Day	16% 8% 3 6% 6% 5% 5% 4 6% 8% 34%	2940
July	1st to 10th	Day	13% 6% 3 6% 5% 5% 5% 4 6% 9% 38%	8280
	11th to 20th	Day	10% 4 2 6% 4 4 5% 4 6% 9% 47%	8280
	21st to end	Day	12% 6% 2 6% 5% 4 5% 4 6% 9% 42%	8993
August	1st to 10th	Day	15% 7% 3 8% 5% 5% 5% 4 5% 7% 36%	4501
	11th to 20th	Day	18% 6% 2 6% 4 4 5% 4 6% 7% 37%	4304
	21st to end	Day	11% 6% 2 6% 4 5% 5% 5% 6% 9% 40%	4454
September	1st to 10th	Day	14% 6% 3 6% 4 4 5% 4 6% 7% 40%	2400
	11th to 20th	Day	12% 6% 2 5% 4 4 4 3 5% 7% 47%	2400
	21st to end	Day	17% 8% 2 6% 5% 4 4 3 5% 6% 38%	2109
October	1st to 10th	Day	19% 9% 3 7% 4 4 5% 3 5% 6% 35%	2000
	11th to 20th	Day	19% 12% 4 8% 5% 4 5% 4 5% 6% 28%	2000
	21st to end	Day	25% 11% 3 9% 5% 5% 5% 3 5% 5% 24%	2095
November	1st to 10th	Day	14% 13% 4 8% 5% 4 5% 4 4 7% 33%	1796
	11th to 20th	Day	15% 14% 6% 10% 6% 4 4 4 5% 5% 27%	1680
	21st to end	Day	20% 17% 6% 10% 6% 6% 4 3 4 5% 19%	1680
December	1st to 10th	Day	18% 22% 6% 13% 7% 5% 5% 3 4 5% 12%	2680
	11th to 20th	Day	15% 17% 6% 13% 6% 4 4 3 3 3 24%	3066
	21st to end	Day	21% 18% 6% 15% 5% 4 3 3 3 4 19%	4048
January	1st to 10th	Night	12% 15% 8% 16% 8% 5% 5% 3 4 5% 18%	8234
	11th to 20th	Night	10% 16% 6% 15% 9% 7% 5% 4 5% 5% 18%	8235
	21st to end	Night	9% 16% 6% 13% 8% 7% 6% 4 5% 5% 21%	8623
February	1st to 10th	Night	11% 15% 6% 12% 7% 6% 5% 4 5% 5% 23%	2730
	11th to 20th	Night	11% 14% 6% 11% 6% 6% 5% 3 4 6% 28%	2663
	21st to end	Night	12% 13% 5% 9% 7% 6% 5% 3 7% 6% 27%	2123
March	1st to 10th	Night	19% 15% 5% 10% 6% 5% 4 3 3 3 28%	5311
	11th to 20th	Night	10% 13% 5% 9% 6% 5% 6% 5% 7% 8% 27%	5089
	21st to end	Night	16% 12% 3 9% 6% 5% 4 3 4 6% 31%	5383
April	1st to 10th	Night	19% 12% 3 8% 5% 4 4 3 5% 5% 31%	2100
	11th to 20th	Night	19% 11% 2 7% 4 5% 3 3 4 6% 37%	2075
	21st to end	Night	19% 9% 3 7% 4 5% 4 4 5% 6% 33%	1958
May	1st to 10th	Night	19% 10% 3 8% 5% 5% 5% 4 6% 7% 29%	4665
	11th to 20th	Night	14% 7% 3 7% 4 4 4 3 5% 7% 41%	4639
	21st to end	Night	19% 6% 3 6% 4 4 5% 3 6% 8% 35%	5114
June	1st to 10th	Night	16% 6% 3 7% 5% 4 5% 4 7% 6% 36%	1680
	11th to 20th	Night	13% 7% 2 7% 4 4 5% 3 6% 6% 44%	1680
	21st to end	Night	17% 6% 2 6% 5% 5% 4 4 6% 8% 37%	1680
July	1st to 10th	Night	11% 6% 2 6% 5% 4 5% 4 6% 9% 41%	4680
	11th to 20th	Night	11% 5% 1 5% 4 4 4 3 5% 7% 50%	4680
	21st to end	Night	11% 6% 2 6% 5% 4 4 4 6% 7% 45%	5084
August	1st to 10th	Night	12% 5% 2 6% 4 5% 5% 4 6% 8% 43%	2864
	11th to 20th	Night	15% 5% 2 6% 4 5% 4 3 5% 7% 45%	2965
	21st to end	Night	12% 6% 2 5% 4 4 4 4 6% 8% 45%	3608
September	1st to 10th	Night	11% 6% 2 5% 4 5% 5% 4 5% 7% 47%	2000
	11th to 20th	Night	13% 5% 1 4 3 4 3 3 5% 6% 52%	2000
	21st to end	Night	16% 7% 3 5% 5% 4 4 3 5% 7% 42%	2287
October	1st to 10th	Night	18% 8% 3 6% 4 4 4 3 5% 6% 41%	2400
	11th to 20th	Night	18% 11% 3 8% 5% 5% 4 4 5% 6% 31%	2400
	21st to end	Night	21% 12% 3 8% 5% 5% 5% 3 5% 6% 28%	2745
November	1st to 10th	Night	15% 14% 3 7% 5% 4 4 3 5% 5% 34%	2720
	11th to 20th	Night	16% 13% 4 9% 6% 5% 5% 4 5% 6% 28%	2940
	21st to end	Night	18% 17% 5% 11% 5% 4 4 3 5% 6% 21%	2940
December	1st to 10th	Night	17% 18% 5% 13% 6% 5% 5% 4 5% 6% 16%	4720
	11th to 20th	Night	19% 16% 6% 12% 6% 4 4 3 4 4 24%	5348
	21st to end	Night	23% 18% 5% 13% 6% 4 3 2 3 3 20%	7150

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	65% 8% 10% 11% 5%	4662
	11th to 20th	Day	69% 6% 8% 8% 9% 1	4680
	21st to end	Day	69% 5% 7% 10% 8% 1	5541
February	1st to 10th	Day	63% 6% 9% 15% 6% 1	1890
	11th to 20th	Day	58% 5% 12% 15% 9% 1	1852
	21st to end	Day	61% 7% 9% 12% 9% 2	1683
March	1st to 10th	Day	59% 5% 9% 11% 14% 2	4737
	11th to 20th	Day	53% 7% 14% 15% 9% 2	5090
	21st to end	Day	49% 5% 7% 19% 17% 3	5790
April	1st to 10th	Day	55% 6% 8% 16% 12% 3	2520
	11th to 20th	Day	52% 5% 7% 19% 15% 2	2494
	21st to end	Day	53% 6% 8% 16% 14% 3	2680
May	1st to 10th	Day	51% 7% 10% 20% 10% 2	8244
	11th to 20th	Day	46% 9% 12% 19% 13% 1	8225
	21st to end	Day	47% 6% 11% 22% 13% 1	9061
June	1st to 10th	Day	51% 7% 10% 18% 13% 1	2940
	11th to 20th	Day	43% 8% 11% 22% 13% 2	2940
	21st to end	Day	46% 9% 12% 21% 11% 1	2940
July	1st to 10th	Day	41% 6% 17% 25% 11%	8210
	11th to 20th	Day	32% 7% 13% 33% 14% 1	8205
	21st to end	Day	37% 7% 14% 33% 9%	8795
August	1st to 10th	Day	46% 7% 14% 22% 10% 1	4487
	11th to 20th	Day	44% 7% 16% 26% 7% 1	4343
	21st to end	Day	37% 8% 15% 30% 10% 1	4454
September	1st to 10th	Day	40% 8% 14% 27% 11%	2400
	11th to 20th	Day	35% 9% 13% 29% 15%	2400
	21st to end	Day	46% 7% 14% 22% 11%	2109
October	1st to 10th	Day	48% 5% 10% 29% 8%	3260
	11th to 20th	Day	47% 6% 13% 21% 12% 1	3240
	21st to end	Day	53% 6% 16% 18% 6% 1	3359
November	1st to 10th	Day	50% 8% 14% 21% 7% 1	1796
	11th to 20th	Day	58% 6% 13% 14% 9% 1	1680
	21st to end	Day	66% 7% 10% 10% 6% 1	1680
December	1st to 10th	Day	74% 6% 10% 7% 2	2680
	11th to 20th	Day	65% 6% 9% 13% 7%	3066
	21st to end	Day	70% 4 8% 13% 5%	4048
January	1st to 10th	Night	67% 7% 10% 11% 5%	8234
	11th to 20th	Night	65% 7% 10% 11% 7%	8280
	21st to end	Night	63% 6% 7% 11% 11% 1	8623
February	1st to 10th	Night	60% 7% 10% 16% 6% 1	2730
	11th to 20th	Night	57% 6% 10% 19% 7% 1	2665
	21st to end	Night	55% 8% 9% 17% 9% 1	2123
March	1st to 10th	Night	60% 5% 8% 15% 9% 4	5321
	11th to 20th	Night	49% 9% 17% 15% 7% 2	5090
	21st to end	Night	50% 6% 10% 19% 12% 2	5383
April	1st to 10th	Night	53% 5% 9% 18% 12% 2	2100
	11th to 20th	Night	49% 6% 8% 22% 14% 1	2075
	21st to end	Night	50% 6% 9% 17% 16% 2	1958
May	1st to 10th	Night	51% 7% 10% 20% 9% 3	4671
	11th to 20th	Night	39% 9% 14% 22% 14% 2	4640
	21st to end	Night	44% 8% 13% 20% 15% 1	5115
June	1st to 10th	Night	43% 9% 12% 22% 12% 1	1680
	11th to 20th	Night	38% 8% 12% 24% 16% 2	1680
	21st to end	Night	43% 8% 16% 20% 12% 1	1680
July	1st to 10th	Night	39% 8% 18% 21% 14% 1	4640
	11th to 20th	Night	32% 5% 14% 33% 15%	4632
	21st to end	Night	37% 7% 13% 29% 13%	4967
August	1st to 10th	Night	37% 7% 16% 26% 12% 2	2854
	11th to 20th	Night	37% 7% 16% 30% 9% 1	2992
	21st to end	Night	36% 7% 16% 29% 10% 2	3608
September	1st to 10th	Night	34% 9% 15% 28% 13% 1	2000
	11th to 20th	Night	33% 6% 14% 35% 11% 1	2000
	21st to end	Night	41% 7% 13% 28% 10%	2287
October	1st to 10th	Night	38% 6% 12% 29% 15%	3920
	11th to 20th	Night	45% 7% 16% 21% 10%	3899
	21st to end	Night	49% 7% 16% 20% 7%	4431
November	1st to 10th	Night	51% 7% 14% 20% 8%	2720
	11th to 20th	Night	56% 7% 11% 17% 7% 1	2940
	21st to end	Night	62% 8% 11% 15% 4	2940
December	1st to 10th	Night	68% 8% 13% 10% 2	4720
	11th to 20th	Night	64% 5% 8% 13% 10% 1	5348
	21st to end	Night	70% 5% 6% 11% 8%	7150

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% 20% 40% 13% 4	220
	11th to 20th	Day	30% 21% 35% 10% 3	220
	21st to end	Day	22% 25% 37% 12% 3 1	319
February	1st to 10th	Day	30% 25% 32% 8% 4	330
	11th to 20th	Day	30% 26% 39% 3 1	330
	21st to end	Day	33% 25% 33% 8% 1	399
March	1st to 10th	Day	27% 25% 35% 11% 2	540
	11th to 20th	Day	30% 21% 31% 14% 3 1	540
	21st to end	Day	32% 24% 28% 12% 4	594
April	1st to 10th	Day	33% 22% 29% 11% 5%	540
	11th to 20th	Day	35% 23% 19% 15% 7% 1	532
	21st to end	Day	32% 18% 32% 11% 6% 1	540
May	1st to 10th	Day	26% 20% 31% 15% 6% 2	543
	11th to 20th	Day	20% 17% 34% 19% 7% 2	567
	21st to end	Day	21% 19% 32% 18% 6% 3	617
June	1st to 10th	Day	24% 15% 35% 19% 8% 1	570
	11th to 20th	Day	17% 17% 33% 20% 10% 2	570
	21st to end	Day	18% 16% 35% 20% 10% 2	570
July	1st to 10th	Day	10% 10% 36% 31% 9% 3	565
	11th to 20th	Day	14% 12% 34% 26% 10% 3	564
	21st to end	Day	15% 10% 35% 26% 10% 3	620
August	1st to 10th	Day	15% 7% 33% 29% 12% 4	566
	11th to 20th	Day	13% 10% 31% 28% 13% 5%	559
	21st to end	Day	14% 13% 32% 24% 11% 5%	619
September	1st to 10th	Day	16% 14% 30% 21% 13% 7%	530
	11th to 20th	Day	11% 11% 24% 25% 17% 11%	530
	21st to end	Day	18% 15% 30% 20% 12% 5%	530
October	1st to 10th	Day	23% 19% 24% 21% 10% 4	530
	11th to 20th	Day	26% 23% 32% 13% 5% 2	530
	21st to end	Day	29% 19% 31% 17% 4	525
November	1st to 10th	Day	29% 19% 29% 15% 6% 1	370
	11th to 20th	Day	28% 23% 31% 10% 5% 2	220
	21st to end	Day	35% 23% 33% 6% 2 1	220
December	1st to 10th	Day	30% 19% 37% 13% 1	220
	11th to 20th	Day	32% 30% 29% 7% 2 1	220
	21st to end	Day	31% 24% 29% 12% 4	242
January	1st to 10th	Night	25% 22% 34% 16% 3	840
	11th to 20th	Night	27% 22% 29% 17% 5% 1	840
	21st to end	Night	19% 18% 38% 21% 4	924
February	1st to 10th	Night	20% 20% 38% 20% 2	840
	11th to 20th	Night	20% 22% 42% 13% 3	823
	21st to end	Night	23% 22% 33% 20% 3	692
March	1st to 10th	Night	26% 19% 34% 17% 3	840
	11th to 20th	Night	25% 22% 31% 18% 4 1	840
	21st to end	Night	25% 17% 32% 19% 6%	924
April	1st to 10th	Night	29% 17% 32% 19% 3	840
	11th to 20th	Night	24% 22% 30% 19% 6%	831
	21st to end	Night	24% 16% 29% 24% 7%	698
May	1st to 10th	Night	23% 13% 28% 27% 9% 1	425
	11th to 20th	Night	21% 11% 35% 27% 7%	414
	21st to end	Night	15% 11% 36% 28% 10%	455
June	1st to 10th	Night	16% 9% 35% 32% 7%	420
	11th to 20th	Night	14% 15% 34% 28% 9%	420
	21st to end	Night	20% 9% 30% 30% 12%	420
July	1st to 10th	Night	7% 10% 34% 37% 11% 1	410
	11th to 20th	Night	11% 8% 29% 39% 12%	408
	21st to end	Night	9% 6% 31% 41% 12%	460
August	1st to 10th	Night	11% 5% 26% 41% 17%	538
	11th to 20th	Night	12% 4 24% 39% 19% 2	624
	21st to end	Night	13% 9% 30% 30% 16% 2	874
September	1st to 10th	Night	14% 9% 32% 29% 15% 1	800
	11th to 20th	Night	16% 7% 23% 31% 20% 4	800
	21st to end	Night	20% 12% 23% 26% 18% 2	800
October	1st to 10th	Night	21% 14% 27% 24% 12% 2	800
	11th to 20th	Night	25% 16% 33% 19% 7% 1	800
	21st to end	Night	28% 17% 29% 21% 5%	880
November	1st to 10th	Night	26% 17% 30% 22% 4 1	820
	11th to 20th	Night	22% 22% 32% 15% 8% 1	840
	21st to end	Night	31% 19% 27% 18% 4	840
December	1st to 10th	Night	28% 21% 32% 16% 3	840
	11th to 20th	Night	27% 23% 29% 18% 2	840
	21st to end	Night	32% 19% 31% 15% 3	924

Page generated at 2026-08-27 04:07:09. Version ac07

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