Kevin's Cabin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kevin's Cabin clear sky chart from 2005-11-06 to 2024-11-06.

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	13% 10% 4 9% 5% 5% 5% 4 6% 7% 33%	101874
	Night	12% 11% 4 10% 6% 5% 5% 4 5% 6% 31%	97334
Transparency	Day	48% 7% 14% 22% 8%	105346
	Night	52% 6% 13% 21% 8%	101953
Seeing	Day	18% 14% 34% 23% 9% 2	16218
	Night	18% 10% 33% 28% 10% 1	26113

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	7% 13% 7% 15% 7% 8% 6% 5% 6% 6% 20%	2218
	11th to 20th	Day	5% 11% 5% 14% 9% 10% 11% 7% 6% 6% 15%	2220
	21st to end	Day	9% 17% 10% 19% 7% 6% 6% 4 6% 4 13%	2830
February	1st to 10th	Day	8% 12% 6% 12% 7% 7% 8% 5% 7% 7% 21%	1710
	11th to 20th	Day	7% 12% 4 11% 8% 6% 6% 4 5% 6% 30%	1664
	21st to end	Day	7% 11% 5% 14% 6% 6% 4 4 6% 7% 29%	1413
March	1st to 10th	Day	10% 12% 3 7% 5% 4 4 4 5% 7% 38%	3318
	11th to 20th	Day	6% 11% 5% 14% 9% 5% 4 3 5% 7% 30%	3480
	21st to end	Day	13% 15% 5% 9% 6% 4 3 2 4 6% 33%	3863
April	1st to 10th	Day	14% 12% 3 8% 4 4 5% 3 5% 7% 35%	2280
	11th to 20th	Day	15% 12% 3 8% 4 4 5% 4 6% 7% 32%	2383
	21st to end	Day	17% 12% 3 8% 5% 5% 4 3 5% 6% 34%	2479
May	1st to 10th	Day	18% 10% 3 7% 4 4 4 4 6% 8% 33%	4428
	11th to 20th	Day	15% 9% 3 8% 6% 5% 5% 4 6% 7% 34%	4399
	21st to end	Day	21% 9% 3 6% 4 3 4 3 5% 6% 37%	4983
June	1st to 10th	Day	14% 7% 3 6% 6% 4 5% 4 6% 7% 38%	2850
	11th to 20th	Day	17% 7% 2 8% 5% 5% 4 4 6% 6% 35%	2850
	21st to end	Day	15% 6% 3 8% 5% 4 5% 4 7% 9% 31%	2850
July	1st to 10th	Day	8% 5% 2 6% 5% 5% 5% 5% 8% 11% 40%	4750
	11th to 20th	Day	10% 5% 1 4 4 4 4 4 7% 10% 48%	4750
	21st to end	Day	13% 7% 3 6% 5% 4 4 4 6% 8% 41%	4950
August	1st to 10th	Day	10% 7% 3 8% 4 5% 5% 4 7% 9% 39%	4282
	11th to 20th	Day	12% 5% 2 5% 4 4 5% 4 7% 9% 44%	4041
	21st to end	Day	15% 7% 2 6% 4 4 4 4 5% 8% 39%	4475
September	1st to 10th	Day	13% 6% 2 6% 4 4 4 4 6% 8% 43%	2280
	11th to 20th	Day	16% 7% 2 7% 4 6% 4 4 5% 7% 37%	2234
	21st to end	Day	21% 7% 3 7% 4 3 3 3 4 7% 37%	2011
October	1st to 10th	Day	18% 14% 4 8% 4 5% 4 3 5% 6% 29%	1900
	11th to 20th	Day	19% 15% 5% 9% 4 4 4 3 5% 5% 26%	1900
	21st to end	Day	19% 20% 4 11% 4 4 3 2 4 5% 23%	1929
November	1st to 10th	Day	16% 19% 6% 11% 5% 4 4 3 5% 4 22%	1527
	11th to 20th	Day	13% 19% 6% 19% 6% 5% 4 3 4 4 17%	1520
	21st to end	Day	13% 17% 7% 17% 9% 6% 3 3 4 4 17%	1520
December	1st to 10th	Day	9% 14% 6% 19% 12% 7% 6% 5% 3 6% 14%	1466
	11th to 20th	Day	10% 20% 6% 14% 7% 6% 6% 4 4 5% 20%	1679
	21st to end	Day	16% 18% 8% 14% 8% 5% 4 2 5% 4 16%	2442
January	1st to 10th	Night	5% 15% 6% 15% 10% 7% 6% 5% 5% 6% 21%	4737
	11th to 20th	Night	7% 11% 5% 14% 12% 13% 9% 6% 6% 4 14%	4750
	21st to end	Night	9% 19% 12% 15% 7% 5% 4 3 6% 4 15%	4819
February	1st to 10th	Night	7% 11% 5% 13% 8% 7% 7% 6% 7% 6% 24%	2470
	11th to 20th	Night	8% 10% 3 10% 7% 5% 5% 5% 6% 6% 34%	2403
	21st to end	Night	6% 11% 6% 12% 7% 6% 6% 5% 6% 6% 27%	2041
March	1st to 10th	Night	12% 11% 5% 10% 5% 4 5% 3 5% 7% 34%	3552
	11th to 20th	Night	7% 11% 4 10% 9% 7% 5% 4 5% 7% 30%	3479
	21st to end	Night	17% 15% 4 9% 5% 4 3 3 4 5% 31%	3767
April	1st to 10th	Night	14% 11% 3 7% 6% 4 5% 3 5% 5% 35%	1900
	11th to 20th	Night	16% 13% 4 7% 4 3 4 3 4 7% 36%	1745
	21st to end	Night	17% 11% 4 8% 5% 4 5% 3 4 5% 33%	1701
May	1st to 10th	Night	19% 9% 2 6% 3 4 4 4 6% 6% 38%	2523
	11th to 20th	Night	15% 8% 3 7% 5% 4 4 4 6% 7% 37%	2506
	21st to end	Night	22% 6% 2 5% 4 3 4 3 5% 6% 39%	2601
June	1st to 10th	Night	16% 5% 2 5% 6% 4 3 3 6% 8% 42%	1330
	11th to 20th	Night	14% 5% 3 6% 4 4 5% 4 5% 6% 44%	1330
	21st to end	Night	14% 5% 2 6% 4 4 4 4 5% 9% 43%	1330
July	1st to 10th	Night	9% 4 1 4 3 4 5% 5% 7% 10% 49%	2220
	11th to 20th	Night	6% 3 2 4 3 4 4 4 6% 11% 53%	2220
	21st to end	Night	9% 5% 2 5% 3 4 4 3 6% 8% 50%	2612
August	1st to 10th	Night	8% 5% 2 6% 4 5% 5% 5% 6% 8% 45%	2643
	11th to 20th	Night	11% 6% 2 5% 3 3 4 3 6% 9% 48%	2798
	21st to end	Night	14% 5% 2 6% 4 4 3 3 5% 7% 46%	3189
September	1st to 10th	Night	11% 5% 2 7% 4 4 4 3 4 7% 49%	1900
	11th to 20th	Night	15% 7% 2 6% 4 4 3 3 5% 7% 45%	1943
	21st to end	Night	18% 8% 3 6% 3 3 4 3 5% 7% 40%	2149
October	1st to 10th	Night	15% 12% 3 7% 4 5% 5% 3 5% 7% 34%	2280
	11th to 20th	Night	19% 14% 4 8% 4 4 5% 3 4 6% 31%	2280
	21st to end	Night	18% 15% 4 10% 5% 4 4 4 6% 5% 24%	2667
November	1st to 10th	Night	15% 19% 6% 11% 5% 4 4 3 4 5% 24%	2674
	11th to 20th	Night	14% 16% 6% 17% 8% 5% 4 3 4 5% 17%	2660
	21st to end	Night	13% 16% 6% 14% 9% 6% 5% 3 5% 5% 19%	2660
December	1st to 10th	Night	8% 13% 6% 18% 12% 8% 6% 4 4 6% 15%	2712
	11th to 20th	Night	10% 16% 6% 15% 8% 7% 6% 4 6% 5% 17%	3518
	21st to end	Night	18% 16% 7% 15% 9% 6% 4 4 4 4 13%	5225

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% 7% 9% 16% 6%	2219
	11th to 20th	Day	64% 7% 11% 14% 3	2220
	21st to end	Day	71% 6% 9% 11% 4	2830
February	1st to 10th	Day	59% 6% 10% 14% 9% 1	1710
	11th to 20th	Day	54% 5% 11% 21% 9% 1	1673
	21st to end	Day	53% 6% 12% 16% 13% 1	1413
March	1st to 10th	Day	44% 6% 13% 20% 16% 1	3320
	11th to 20th	Day	52% 7% 14% 20% 8%	3480
	21st to end	Day	54% 4 8% 22% 11% 1	3863
April	1st to 10th	Day	49% 5% 8% 21% 15% 1	2280
	11th to 20th	Day	50% 6% 10% 20% 12% 1	2383
	21st to end	Day	52% 4 10% 22% 11% 1	2479
May	1st to 10th	Day	46% 7% 13% 23% 11% 1	4440
	11th to 20th	Day	47% 8% 12% 19% 12% 1	4403
	21st to end	Day	48% 6% 10% 25% 11% 1	4983
June	1st to 10th	Day	42% 9% 14% 23% 11% 1	2850
	11th to 20th	Day	46% 7% 13% 22% 11%	2850
	21st to end	Day	46% 9% 16% 23% 7%	2850
July	1st to 10th	Day	33% 10% 21% 29% 7%	4676
	11th to 20th	Day	29% 7% 21% 35% 8%	4669
	21st to end	Day	41% 7% 15% 31% 6% 1	4793
August	1st to 10th	Day	39% 7% 16% 24% 12% 1	4267
	11th to 20th	Day	34% 8% 26% 26% 6%	4080
	21st to end	Day	41% 7% 21% 26% 5%	4474
September	1st to 10th	Day	38% 6% 16% 30% 9%	2280
	11th to 20th	Day	45% 7% 21% 22% 5%	2234
	21st to end	Day	47% 5% 14% 27% 6%	2011
October	1st to 10th	Day	44% 6% 17% 26% 8%	3160
	11th to 20th	Day	47% 5% 15% 19% 13%	3140
	21st to end	Day	56% 5% 16% 18% 3	3161
November	1st to 10th	Day	64% 6% 12% 13% 4 1	1527
	11th to 20th	Day	71% 5% 9% 10% 4	1520
	21st to end	Day	71% 6% 11% 10% 3	1520
December	1st to 10th	Day	73% 6% 8% 10% 3 1	1466
	11th to 20th	Day	66% 5% 11% 15% 2	1680
	21st to end	Day	71% 4 7% 14% 5%	2442
January	1st to 10th	Night	63% 6% 11% 16% 4	4737
	11th to 20th	Night	69% 6% 9% 13% 3	4750
	21st to end	Night	71% 5% 10% 11% 3	4819
February	1st to 10th	Night	56% 6% 13% 15% 9% 1	2470
	11th to 20th	Night	49% 6% 13% 21% 10% 1	2404
	21st to end	Night	54% 7% 11% 18% 9%	2041
March	1st to 10th	Night	48% 6% 13% 20% 13% 1	3563
	11th to 20th	Night	51% 8% 14% 19% 7% 1	3480
	21st to end	Night	56% 4 9% 17% 12% 1	3767
April	1st to 10th	Night	49% 5% 8% 20% 16% 1	1900
	11th to 20th	Night	49% 4 10% 21% 14% 2	1745
	21st to end	Night	52% 5% 9% 21% 12% 1	1701
May	1st to 10th	Night	44% 6% 9% 26% 15% 1	2530
	11th to 20th	Night	42% 9% 14% 22% 12% 2	2507
	21st to end	Night	45% 8% 11% 25% 11% 1	2602
June	1st to 10th	Night	39% 8% 16% 24% 13% 1	1330
	11th to 20th	Night	39% 6% 12% 27% 15% 1	1330
	21st to end	Night	38% 7% 19% 27% 8% 1	1330
July	1st to 10th	Night	28% 12% 24% 27% 8% 1	2185
	11th to 20th	Night	24% 7% 20% 37% 11%	2178
	21st to end	Night	30% 7% 16% 37% 8% 1	2529
August	1st to 10th	Night	35% 7% 16% 32% 10% 1	2634
	11th to 20th	Night	30% 8% 24% 32% 6%	2825
	21st to end	Night	37% 7% 22% 28% 7%	3189
September	1st to 10th	Night	35% 6% 17% 32% 11%	1900
	11th to 20th	Night	39% 7% 19% 27% 7%	1943
	21st to end	Night	45% 6% 14% 29% 6%	2149
October	1st to 10th	Night	40% 6% 13% 33% 7%	3800
	11th to 20th	Night	47% 4 15% 26% 8%	3779
	21st to end	Night	55% 6% 12% 21% 6%	4389
November	1st to 10th	Night	63% 5% 12% 15% 5% 1	2674
	11th to 20th	Night	70% 6% 9% 10% 4	2660
	21st to end	Night	67% 7% 12% 10% 3	2660
December	1st to 10th	Night	70% 6% 11% 11% 2	2712
	11th to 20th	Night	67% 6% 10% 12% 4	3516
	21st to end	Night	73% 6% 7% 11% 4	5225

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	13% 18% 33% 26% 9% 1	270
	11th to 20th	Day	15% 12% 41% 26% 6% 1	270
	21st to end	Day	18% 9% 39% 24% 9% 1	297
February	1st to 10th	Day	17% 12% 44% 21% 5% 1	270
	11th to 20th	Day	13% 23% 34% 20% 7% 3	270
	21st to end	Day	20% 19% 43% 13% 4 1	225
March	1st to 10th	Day	15% 16% 39% 19% 10% 1	270
	11th to 20th	Day	14% 19% 36% 21% 9% 2	270
	21st to end	Day	18% 19% 36% 21% 6% 1	321
April	1st to 10th	Day	21% 15% 31% 25% 7%	460
	11th to 20th	Day	26% 15% 30% 22% 6% 1	581
	21st to end	Day	21% 14% 33% 23% 9% 1	650
May	1st to 10th	Day	23% 15% 37% 17% 6% 1	653
	11th to 20th	Day	21% 14% 35% 20% 9% 2	675
	21st to end	Day	23% 12% 32% 25% 7% 1	734
June	1st to 10th	Day	19% 14% 34% 22% 8% 3	680
	11th to 20th	Day	18% 16% 38% 18% 9% 1	680
	21st to end	Day	17% 11% 34% 25% 10% 4	680
July	1st to 10th	Day	11% 11% 29% 30% 14% 5%	671
	11th to 20th	Day	13% 12% 31% 27% 14% 4	668
	21st to end	Day	10% 11% 32% 26% 16% 5%	739
August	1st to 10th	Day	10% 9% 32% 31% 15% 3	676
	11th to 20th	Day	14% 7% 29% 28% 16% 6%	665
	21st to end	Day	18% 9% 31% 27% 13% 2	717
September	1st to 10th	Day	15% 10% 33% 30% 10% 2	490
	11th to 20th	Day	19% 17% 33% 22% 8% 1	444
	21st to end	Day	27% 15% 33% 18% 7%	300
October	1st to 10th	Day	25% 13% 32% 22% 7%	300
	11th to 20th	Day	21% 20% 36% 21% 3	300
	21st to end	Day	32% 18% 33% 14% 2 1	330
November	1st to 10th	Day	20% 20% 34% 20% 6%	285
	11th to 20th	Day	23% 18% 37% 19% 3	270
	21st to end	Day	29% 21% 38% 10% 2	270
December	1st to 10th	Day	20% 13% 37% 22% 7% 1	270
	11th to 20th	Day	21% 17% 39% 20% 3	270
	21st to end	Day	19% 14% 40% 20% 6% 1	297
January	1st to 10th	Night	14% 12% 39% 23% 10% 2	950
	11th to 20th	Night	16% 10% 38% 27% 7% 1	950
	21st to end	Night	16% 12% 38% 27% 7% 1	1045
February	1st to 10th	Night	13% 10% 35% 33% 8% 1	950
	11th to 20th	Night	14% 12% 36% 24% 11% 2	929
	21st to end	Night	12% 11% 39% 25% 9% 3	785
March	1st to 10th	Night	14% 13% 37% 26% 9% 1	668
	11th to 20th	Night	15% 13% 38% 26% 7% 1	570
	21st to end	Night	21% 8% 32% 24% 12% 3	627
April	1st to 10th	Night	19% 11% 34% 27% 9% 1	570
	11th to 20th	Night	23% 10% 31% 27% 8%	563
	21st to end	Night	22% 9% 29% 29% 10%	570
May	1st to 10th	Night	22% 9% 31% 30% 7% 1	570
	11th to 20th	Night	21% 9% 34% 23% 11% 2	561
	21st to end	Night	20% 8% 29% 33% 10%	617
June	1st to 10th	Night	16% 9% 29% 33% 12% 1	570
	11th to 20th	Night	15% 9% 33% 29% 12% 1	570
	21st to end	Night	15% 6% 26% 34% 18% 1	570
July	1st to 10th	Night	9% 5% 25% 39% 21% 2	555
	11th to 20th	Night	11% 7% 26% 36% 18% 1	552
	21st to end	Night	8% 5% 27% 36% 22% 2	624
August	1st to 10th	Night	8% 4 28% 40% 18% 2	567
	11th to 20th	Night	13% 4 23% 34% 22% 4	564
	21st to end	Night	15% 6% 27% 31% 20% 1	627
September	1st to 10th	Night	13% 7% 31% 32% 15% 2	570
	11th to 20th	Night	17% 9% 28% 31% 14% 1	570
	21st to end	Night	23% 8% 33% 24% 12% 1	629
October	1st to 10th	Night	22% 13% 30% 29% 6%	760
	11th to 20th	Night	26% 12% 32% 23% 7% 1	760
	21st to end	Night	27% 13% 33% 21% 5% 1	900
November	1st to 10th	Night	22% 12% 34% 25% 5% 1	955
	11th to 20th	Night	22% 12% 35% 24% 6% 1	950
	21st to end	Night	22% 16% 40% 18% 4	950
December	1st to 10th	Night	15% 10% 38% 26% 9% 2	950
	11th to 20th	Night	19% 13% 37% 24% 6% 1	950
	21st to end	Night	22% 11% 34% 24% 8% 1	1045

Page generated at 2024-11-03 13:19:01. Version ac07

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