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 2024-10-24.

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	16% 11% 4 9% 5% 5% 5% 4 5% 6% 32%	101518
	Night	16% 12% 4 9% 5% 5% 4 3 5% 6% 31%	97258
Transparency	Day	50% 8% 12% 19% 10% 1	101276
	Night	52% 8% 12% 19% 9% 1	97120
Seeing	Day	23% 18% 31% 18% 8% 3	14396
	Night	22% 16% 31% 23% 8% 1	23518

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	13% 15% 7% 14% 9% 5% 5% 4 5% 4 20%	2517
	11th to 20th	Day	12% 14% 7% 16% 9% 6% 4 4 4 4 21%	2520
	21st to end	Day	16% 22% 7% 15% 6% 5% 4 2 3 4 17%	2996
February	1st to 10th	Day	12% 16% 6% 13% 8% 6% 5% 4 5% 4 21%	1710
	11th to 20th	Day	11% 16% 4 12% 7% 5% 5% 3 5% 6% 27%	1663
	21st to end	Day	17% 15% 4 10% 6% 6% 5% 4 5% 5% 25%	1527
March	1st to 10th	Day	17% 16% 5% 11% 5% 4 4 3 3 5% 27%	3229
	11th to 20th	Day	10% 17% 6% 12% 6% 5% 4 3 5% 5% 27%	3480
	21st to end	Day	10% 9% 4 8% 5% 4 3 3 5% 6% 43%	3959
April	1st to 10th	Day	20% 14% 4 6% 4 4 4 3 4 6% 30%	2280
	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 4 5% 24%	1916
November	1st to 10th	Day	14% 12% 3 7% 5% 5% 5% 4 4 7% 34%	1622
	11th to 20th	Day	16% 13% 6% 10% 6% 4 4 4 5% 5% 28%	1520
	21st to end	Day	19% 16% 6% 10% 6% 6% 5% 3 4 5% 19%	1520
December	1st to 10th	Day	19% 21% 5% 12% 7% 5% 5% 3 4 4 14%	1520
	11th to 20th	Day	18% 16% 5% 11% 6% 4 4 3 4 5% 25%	1906
	21st to end	Day	25% 19% 6% 16% 4 3 2 2 2 3 18%	2772
January	1st to 10th	Night	15% 16% 7% 14% 7% 5% 5% 3 4 6% 17%	4429
	11th to 20th	Night	11% 13% 5% 14% 9% 8% 6% 4 5% 6% 21%	4440
	21st to end	Night	15% 19% 7% 12% 6% 7% 4 3 3 4 19%	4657
February	1st to 10th	Night	12% 15% 6% 12% 7% 6% 5% 4 5% 6% 23%	2470
	11th to 20th	Night	11% 14% 6% 11% 6% 6% 4 3 4 6% 29%	2403
	21st to end	Night	13% 12% 5% 9% 7% 6% 5% 3 7% 6% 28%	1927
March	1st to 10th	Night	19% 13% 4 10% 6% 4 3 2 3 4 31%	3610
	11th to 20th	Night	13% 17% 6% 10% 6% 5% 4 4 5% 6% 24%	3479
	21st to end	Night	12% 10% 3 9% 6% 5% 4 4 4 6% 37%	3672
April	1st to 10th	Night	19% 12% 3 7% 5% 4 4 3 4 6% 32%	1900
	11th to 20th	Night	18% 10% 2 7% 4 6% 3 3 4 6% 37%	1875
	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% 4 3 5% 6% 26%	2507
November	1st to 10th	Night	16% 13% 3 7% 5% 4 4 3 5% 5% 35%	2454
	11th to 20th	Night	17% 13% 4 9% 6% 5% 5% 4 5% 6% 27%	2660
	21st to end	Night	19% 16% 5% 10% 5% 4 4 3 5% 7% 22%	2660
December	1st to 10th	Night	18% 19% 5% 13% 6% 4 4 4 4 5% 18%	2660
	11th to 20th	Night	18% 18% 5% 10% 6% 4 4 2 3 4 25%	3288
	21st to end	Night	26% 19% 5% 14% 5% 4 4 2 3 3 15%	4884

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	63% 11% 11% 8% 6% 1	2518
	11th to 20th	Day	65% 8% 9% 10% 6% 1	2520
	21st to end	Day	72% 6% 7% 9% 6% 1	2996
February	1st to 10th	Day	64% 7% 9% 14% 5% 1	1710
	11th to 20th	Day	57% 6% 12% 14% 9% 1	1672
	21st to end	Day	59% 8% 10% 12% 10% 2	1527
March	1st to 10th	Day	59% 6% 9% 14% 11% 1	3232
	11th to 20th	Day	55% 8% 11% 15% 9% 2	3480
	21st to end	Day	40% 6% 9% 24% 16% 4	3959
April	1st to 10th	Day	54% 6% 8% 17% 12% 3	2280
	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	52% 6% 10% 21% 11% 1	1900
	11th to 20th	Day	56% 8% 13% 17% 6% 1	1900
	21st to end	Day	61% 7% 11% 14% 6% 1	1916
November	1st to 10th	Day	48% 8% 15% 21% 7% 1	1622
	11th to 20th	Day	58% 6% 13% 13% 9% 1	1520
	21st to end	Day	66% 8% 10% 10% 6% 1	1520
December	1st to 10th	Day	72% 7% 9% 9% 3	1520
	11th to 20th	Day	61% 8% 13% 12% 6% 1	1906
	21st to end	Day	73% 3 6% 13% 3	2772
January	1st to 10th	Night	66% 9% 12% 10% 3	4429
	11th to 20th	Night	61% 10% 14% 10% 4 1	4440
	21st to end	Night	69% 7% 8% 9% 6%	4657
February	1st to 10th	Night	61% 7% 11% 15% 6% 1	2470
	11th to 20th	Night	56% 6% 11% 19% 7% 1	2405
	21st to end	Night	54% 8% 10% 17% 10% 1	1927
March	1st to 10th	Night	56% 6% 10% 19% 9% 1	3620
	11th to 20th	Night	55% 10% 13% 14% 7% 1	3480
	21st to end	Night	42% 8% 11% 21% 14% 3	3672
April	1st to 10th	Night	53% 6% 9% 18% 13% 2	1900
	11th to 20th	Night	48% 6% 8% 22% 14% 2	1875
	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	45% 7% 12% 21% 15%	2280
	11th to 20th	Night	53% 9% 12% 18% 8%	2280
	21st to end	Night	57% 8% 13% 15% 8%	2507
November	1st to 10th	Night	49% 7% 15% 20% 9%	2454
	11th to 20th	Night	56% 8% 12% 16% 8% 1	2660
	21st to end	Night	61% 8% 12% 14% 4	2660
December	1st to 10th	Night	68% 7% 10% 12% 3	2660
	11th to 20th	Night	63% 6% 10% 13% 7% 1	3288
	21st to end	Night	74% 6% 7% 11% 2	4884

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% 21% 37% 13% 4 1	180
	11th to 20th	Day	29% 22% 35% 11% 3	180
	21st to end	Day	23% 23% 36% 13% 4 1	261
February	1st to 10th	Day	30% 27% 31% 9% 3	270
	11th to 20th	Day	31% 26% 39% 3 1	270
	21st to end	Day	33% 27% 31% 8% 1	339
March	1st to 10th	Day	26% 23% 36% 12% 3	460
	11th to 20th	Day	27% 21% 33% 15% 3 1	460
	21st to end	Day	30% 24% 28% 12% 5%	506
April	1st to 10th	Day	31% 21% 30% 12% 6%	460
	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	31% 18% 31% 16% 4	460
November	1st to 10th	Day	26% 20% 31% 16% 7% 1	316
	11th to 20th	Day	29% 24% 29% 10% 5% 2	180
	21st to end	Day	32% 23% 35% 7% 3 1	180
December	1st to 10th	Day	31% 18% 37% 13% 1	180
	11th to 20th	Day	32% 29% 27% 8% 2 1	180
	21st to end	Day	30% 26% 29% 11% 3 1	198
January	1st to 10th	Night	25% 22% 33% 16% 3	760
	11th to 20th	Night	26% 22% 29% 18% 5% 1	760
	21st to end	Night	18% 17% 38% 22% 4	836
February	1st to 10th	Night	21% 21% 37% 19% 2	760
	11th to 20th	Night	20% 22% 42% 13% 3	743
	21st to end	Night	22% 22% 32% 20% 3	628
March	1st to 10th	Night	25% 19% 34% 18% 4	760
	11th to 20th	Night	24% 23% 30% 18% 4 1	760
	21st to end	Night	23% 17% 33% 21% 6%	836
April	1st to 10th	Night	28% 17% 32% 19% 4	760
	11th to 20th	Night	23% 22% 30% 18% 6%	751
	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% 30% 20% 5%	805
November	1st to 10th	Night	25% 16% 31% 22% 5% 1	740
	11th to 20th	Night	23% 22% 32% 14% 8% 1	760
	21st to end	Night	31% 18% 27% 19% 4	760
December	1st to 10th	Night	29% 21% 32% 16% 3	760
	11th to 20th	Night	28% 22% 30% 18% 2 1	760
	21st to end	Night	32% 18% 32% 15% 3	836

Page generated at 2024-10-21 02:20:05. Version ac07

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