KimbleLabs Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the KimbleLabs Observatory clear sky chart from 2005-11-06 to 2024-08-15.

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% 9% 3 7% 5% 4 4 4 5% 7% 36%	95512
	Night	15% 10% 3 7% 5% 4 4 4 5% 7% 37%	93137
Transparency	Day	46% 7% 12% 21% 13% 2	95276
	Night	46% 6% 11% 21% 13% 2	92978
Seeing	Day	18% 11% 26% 23% 15% 6%	15038
	Night	19% 8% 26% 30% 15% 2	24741

By Month

Percentage Cloud Cover SE (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	16% 18% 6% 8% 4 4 4 4 5% 5% 26%	2527
	11th to 20th	Day	16% 15% 7% 12% 5% 6% 5% 4 4 4 22%	2746
	21st to end	Day	29% 18% 8% 7% 4 3 2 3 3 4 18%	3124
February	1st to 10th	Day	19% 15% 4 9% 5% 4 4 3 4 5% 29%	1805
	11th to 20th	Day	16% 12% 4 11% 5% 5% 3 3 4 6% 31%	1848
	21st to end	Day	19% 13% 5% 9% 6% 3 4 2 4 5% 31%	1570
March	1st to 10th	Day	22% 16% 5% 9% 4 4 4 3 4 4 26%	3144
	11th to 20th	Day	14% 9% 3 6% 4 4 4 4 5% 7% 41%	3480
	21st to end	Day	18% 9% 3 8% 4 4 4 4 5% 7% 34%	3815
April	1st to 10th	Day	14% 11% 3 7% 5% 4 4 4 5% 7% 35%	2242
	11th to 20th	Day	16% 9% 2 7% 4 5% 4 3 5% 7% 39%	2308
	21st to end	Day	18% 8% 3 7% 5% 5% 4 3 5% 6% 36%	2470
May	1st to 10th	Day	21% 9% 4 7% 4 4 5% 4 5% 7% 29%	4082
	11th to 20th	Day	20% 8% 3 6% 4 3 4 3 5% 7% 38%	4081
	21st to end	Day	10% 6% 3 8% 6% 5% 6% 5% 8% 10% 34%	4476
June	1st to 10th	Day	12% 6% 2 6% 5% 5% 5% 5% 7% 8% 40%	2478
	11th to 20th	Day	9% 5% 3 7% 5% 5% 5% 5% 6% 9% 43%	2660
	21st to end	Day	9% 6% 3 6% 5% 4 6% 5% 6% 10% 40%	2660
July	1st to 10th	Day	11% 7% 3 7% 5% 5% 5% 4 7% 9% 37%	4440
	11th to 20th	Day	7% 4 2 6% 5% 4 5% 5% 7% 11% 45%	4294
	21st to end	Day	11% 7% 3 7% 6% 6% 7% 5% 7% 10% 32%	4466
August	1st to 10th	Day	8% 5% 2 5% 4 5% 6% 4 8% 9% 43%	2457
	11th to 20th	Day	9% 6% 3 7% 5% 5% 5% 4 8% 10% 39%	2357
	21st to end	Day	8% 5% 2 6% 5% 4 5% 4 6% 9% 46%	2399
September	1st to 10th	Day	13% 5% 2 6% 3 4 4 4 6% 7% 47%	2050
	11th to 20th	Day	9% 5% 2 5% 4 4 4 3 6% 9% 48%	1980
	21st to end	Day	13% 7% 2 5% 4 4 3 3 5% 6% 49%	1980
October	1st to 10th	Day	10% 6% 2 6% 5% 5% 4 3 5% 6% 47%	1980
	11th to 20th	Day	13% 7% 2 6% 5% 4 3 3 5% 6% 45%	1828
	21st to end	Day	21% 9% 2 7% 4 3 3 2 5% 6% 37%	1841
November	1st to 10th	Day	8% 7% 3 6% 3 4 4 3 4 6% 53%	1672
	11th to 20th	Day	14% 10% 4 9% 4 4 3 3 5% 7% 37%	1710
	21st to end	Day	18% 11% 3 7% 5% 4 4 3 5% 5% 36%	1710
December	1st to 10th	Day	20% 14% 5% 9% 6% 4 5% 3 5% 5% 24%	1710
	11th to 20th	Day	16% 14% 6% 9% 5% 4 5% 3 5% 5% 29%	2153
	21st to end	Day	21% 21% 6% 10% 6% 4 4 3 4 5% 17%	2969
January	1st to 10th	Night	16% 18% 6% 11% 6% 5% 4 4 4 5% 21%	4428
	11th to 20th	Night	15% 17% 6% 15% 6% 5% 4 3 4 5% 21%	4210
	21st to end	Night	26% 18% 6% 8% 4 4 3 3 3 4 21%	4532
February	1st to 10th	Night	21% 12% 3 9% 5% 4 4 4 4 5% 29%	2371
	11th to 20th	Night	15% 11% 4 9% 6% 4 5% 4 5% 6% 31%	2218
	21st to end	Night	21% 13% 4 8% 3 4 4 4 4 6% 30%	1884
March	1st to 10th	Night	22% 14% 3 5% 4 4 3 3 4 5% 33%	3707
	11th to 20th	Night	12% 8% 2 7% 4 4 4 4 5% 6% 44%	3480
	21st to end	Night	17% 8% 3 7% 4 4 4 4 4 6% 39%	3817
April	1st to 10th	Night	14% 9% 3 6% 5% 4 5% 5% 5% 7% 38%	1952
	11th to 20th	Night	15% 8% 2 5% 4 4 3 4 6% 7% 40%	1820
	21st to end	Night	16% 7% 2 6% 5% 4 5% 4 6% 7% 37%	1710
May	1st to 10th	Night	21% 11% 4 9% 5% 5% 4 4 5% 6% 27%	2813
	11th to 20th	Night	18% 7% 2 6% 4 4 4 4 5% 8% 38%	2812
	21st to end	Night	9% 5% 2 6% 4 4 4 4 7% 10% 45%	3079
June	1st to 10th	Night	9% 5% 2 5% 5% 4 4 3 5% 9% 48%	1696
	11th to 20th	Night	8% 6% 2 4 3 4 4 5% 7% 11% 46%	1520
	21st to end	Night	6% 4 2 5% 5% 4 6% 4 8% 10% 46%	1520
July	1st to 10th	Night	12% 6% 2 5% 3 3 4 4 5% 7% 49%	2530
	11th to 20th	Night	6% 4 1 5% 4 4 4 4 7% 9% 52%	2654
	21st to end	Night	10% 7% 3 7% 5% 5% 5% 5% 7% 10% 37%	3087
August	1st to 10th	Night	6% 5% 1 6% 5% 5% 4 4 6% 9% 48%	1701
	11th to 20th	Night	7% 5% 2 6% 4 4 5% 4 6% 9% 47%	1643
	21st to end	Night	6% 3 2 5% 4 3 4 3 7% 10% 53%	1953
September	1st to 10th	Night	13% 5% 2 4 4 3 4 3 5% 7% 50%	1890
	11th to 20th	Night	8% 5% 2 5% 3 4 4 4 5% 7% 55%	1980
	21st to end	Night	12% 6% 2 6% 4 3 4 2 4 6% 51%	1980
October	1st to 10th	Night	8% 5% 2 6% 4 4 3 3 5% 6% 54%	1980
	11th to 20th	Night	15% 7% 2 7% 5% 4 4 3 5% 7% 42%	2132
	21st to end	Night	18% 9% 3 6% 4 4 5% 3 4 5% 40%	2511
November	1st to 10th	Night	13% 8% 2 4 4 3 4 3 4 6% 48%	2406
	11th to 20th	Night	16% 9% 2 7% 4 4 3 3 5% 6% 40%	2470
	21st to end	Night	19% 12% 4 7% 5% 4 4 3 5% 7% 31%	2470
December	1st to 10th	Night	21% 12% 4 9% 4 4 4 4 5% 5% 29%	2470
	11th to 20th	Night	19% 12% 6% 8% 5% 4 3 3 5% 6% 29%	3042
	21st to end	Night	21% 18% 6% 11% 6% 5% 4 3 4 5% 17%	4669

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	59% 5% 11% 15% 9%	2528
	11th to 20th	Day	64% 5% 12% 13% 5%	2746
	21st to end	Day	71% 3 9% 13% 3 1	3124
February	1st to 10th	Day	57% 5% 10% 16% 9% 1	1805
	11th to 20th	Day	56% 4 10% 20% 9% 1	1858
	21st to end	Day	56% 5% 9% 19% 8% 2	1570
March	1st to 10th	Day	60% 6% 7% 18% 8% 1	3144
	11th to 20th	Day	41% 6% 11% 24% 16% 1	3480
	21st to end	Day	47% 7% 12% 22% 11% 1	3815
April	1st to 10th	Day	47% 7% 11% 22% 12% 1	2242
	11th to 20th	Day	45% 5% 11% 22% 14% 3	2308
	21st to end	Day	48% 6% 10% 22% 11% 2	2470
May	1st to 10th	Day	52% 9% 12% 20% 7% 1	4120
	11th to 20th	Day	46% 8% 13% 22% 12%	4085
	21st to end	Day	39% 12% 14% 19% 15% 2	4489
June	1st to 10th	Day	40% 9% 11% 22% 16% 2	2478
	11th to 20th	Day	35% 9% 14% 23% 18% 2	2660
	21st to end	Day	38% 9% 15% 20% 14% 4	2660
July	1st to 10th	Day	43% 5% 12% 20% 18% 2	4371
	11th to 20th	Day	32% 6% 11% 31% 19% 1	4219
	21st to end	Day	45% 7% 14% 17% 13% 3	4324
August	1st to 10th	Day	32% 10% 16% 27% 14% 2	2444
	11th to 20th	Day	37% 8% 13% 27% 14% 1	2357
	21st to end	Day	33% 8% 15% 22% 17% 6%	2399
September	1st to 10th	Day	35% 6% 12% 23% 18% 5%	2050
	11th to 20th	Day	32% 7% 13% 25% 21% 2	1980
	21st to end	Day	37% 5% 11% 24% 22% 2	1980
October	1st to 10th	Day	37% 7% 10% 24% 20% 2	1980
	11th to 20th	Day	39% 5% 10% 24% 20% 2	1828
	21st to end	Day	48% 5% 11% 21% 14% 2	1841
November	1st to 10th	Day	33% 5% 10% 29% 20% 3	1672
	11th to 20th	Day	47% 4 10% 21% 15% 3	1710
	21st to end	Day	51% 4 10% 22% 13% 1	1710
December	1st to 10th	Day	63% 4 11% 17% 5%	1710
	11th to 20th	Day	57% 5% 10% 19% 9%	2150
	21st to end	Day	69% 5% 9% 10% 6%	2969
January	1st to 10th	Night	63% 7% 9% 14% 7%	4428
	11th to 20th	Night	66% 5% 10% 14% 6%	4210
	21st to end	Night	67% 4 9% 15% 5% 1	4532
February	1st to 10th	Night	58% 5% 10% 19% 7% 1	2371
	11th to 20th	Night	53% 5% 10% 20% 11% 1	2219
	21st to end	Night	57% 4 11% 16% 9% 2	1884
March	1st to 10th	Night	52% 5% 8% 23% 10% 1	3707
	11th to 20th	Night	38% 7% 13% 25% 15% 1	3480
	21st to end	Night	45% 6% 10% 27% 11% 1	3817
April	1st to 10th	Night	44% 6% 12% 24% 12% 2	1952
	11th to 20th	Night	40% 6% 11% 18% 19% 5%	1820
	21st to end	Night	45% 6% 12% 20% 13% 3	1710
May	1st to 10th	Night	56% 9% 8% 18% 7% 2	2840
	11th to 20th	Night	42% 8% 14% 25% 9% 1	2813
	21st to end	Night	29% 10% 18% 24% 13% 5%	3087
June	1st to 10th	Night	32% 8% 11% 26% 21% 2	1696
	11th to 20th	Night	30% 8% 15% 22% 20% 4	1520
	21st to end	Night	30% 8% 17% 22% 17% 5%	1520
July	1st to 10th	Night	35% 6% 11% 25% 18% 6%	2490
	11th to 20th	Night	27% 7% 13% 32% 20% 2	2606
	21st to end	Night	40% 6% 13% 23% 14% 4	2988
August	1st to 10th	Night	30% 9% 15% 28% 16% 2	1690
	11th to 20th	Night	31% 9% 14% 28% 17% 1	1643
	21st to end	Night	25% 8% 16% 25% 22% 5%	1953
September	1st to 10th	Night	32% 6% 13% 25% 17% 7%	1890
	11th to 20th	Night	28% 6% 11% 26% 26% 3	1980
	21st to end	Night	35% 5% 9% 22% 26% 3	1980
October	1st to 10th	Night	31% 5% 11% 27% 23% 3	1980
	11th to 20th	Night	40% 6% 9% 24% 20% 2	2132
	21st to end	Night	46% 5% 9% 22% 16% 3	2511
November	1st to 10th	Night	38% 5% 12% 21% 22% 4	2406
	11th to 20th	Night	44% 5% 9% 22% 18% 3	2470
	21st to end	Night	52% 5% 11% 21% 10% 1	2470
December	1st to 10th	Night	56% 6% 11% 19% 8% 1	2470
	11th to 20th	Night	56% 5% 10% 20% 9% 1	3044
	21st to end	Night	69% 6% 9% 12% 4	4669

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	25% 20% 33% 16% 6%	270
	11th to 20th	Day	29% 23% 34% 11% 3	270
	21st to end	Day	33% 20% 29% 15% 3	297
February	1st to 10th	Day	26% 23% 31% 17% 3	270
	11th to 20th	Day	28% 24% 31% 14% 2	270
	21st to end	Day	29% 18% 42% 8% 2	225
March	1st to 10th	Day	25% 25% 34% 13% 2	281
	11th to 20th	Day	27% 15% 33% 19% 6%	460
	21st to end	Day	29% 17% 31% 16% 7%	506
April	1st to 10th	Day	21% 19% 29% 20% 9% 1	460
	11th to 20th	Day	21% 20% 24% 21% 11% 4	452
	21st to end	Day	22% 16% 33% 17% 9% 2	460
May	1st to 10th	Day	23% 14% 31% 19% 9% 4	463
	11th to 20th	Day	22% 9% 27% 22% 14% 6%	487
	21st to end	Day	13% 7% 23% 29% 17% 11%	529
June	1st to 10th	Day	14% 7% 22% 29% 19% 9%	498
	11th to 20th	Day	11% 6% 23% 32% 23% 6%	680
	21st to end	Day	10% 7% 24% 32% 18% 8%	680
July	1st to 10th	Day	13% 4 17% 26% 24% 17%	671
	11th to 20th	Day	9% 4 24% 26% 25% 12%	587
	21st to end	Day	13% 2 18% 28% 26% 13%	532
August	1st to 10th	Day	9% 4 17% 26% 26% 18%	486
	11th to 20th	Day	12% 4 19% 28% 24% 13%	456
	21st to end	Day	12% 3 14% 28% 29% 14%	495
September	1st to 10th	Day	12% 3 18% 24% 32% 11%	450
	11th to 20th	Day	11% 3 14% 26% 32% 13%	450
	21st to end	Day	15% 8% 22% 25% 20% 10%	450
October	1st to 10th	Day	11% 7% 24% 31% 20% 7%	450
	11th to 20th	Day	16% 14% 31% 24% 13% 2	450
	21st to end	Day	25% 14% 33% 23% 5%	356
November	1st to 10th	Day	10% 14% 37% 24% 11% 3	270
	11th to 20th	Day	23% 19% 26% 22% 9% 2	270
	21st to end	Day	25% 14% 38% 19% 5%	270
December	1st to 10th	Day	21% 20% 35% 16% 7% 1	270
	11th to 20th	Day	21% 19% 39% 14% 7%	270
	21st to end	Day	32% 18% 30% 16% 3 1	297
January	1st to 10th	Night	22% 17% 31% 24% 6%	950
	11th to 20th	Night	28% 14% 33% 22% 3	811
	21st to end	Night	25% 14% 32% 27% 3	836
February	1st to 10th	Night	30% 10% 30% 29% 2	760
	11th to 20th	Night	22% 15% 35% 24% 3	743
	21st to end	Night	28% 13% 31% 25% 2	628
March	1st to 10th	Night	22% 11% 35% 26% 5%	760
	11th to 20th	Night	22% 13% 33% 25% 6% 1	760
	21st to end	Night	22% 12% 30% 28% 7%	836
April	1st to 10th	Night	18% 12% 36% 26% 8%	622
	11th to 20th	Night	19% 9% 31% 29% 10% 1	563
	21st to end	Night	18% 8% 37% 28% 9% 1	570
May	1st to 10th	Night	23% 8% 28% 27% 12% 1	570
	11th to 20th	Night	18% 4 25% 34% 18% 2	561
	21st to end	Night	10% 2 23% 34% 27% 3	617
June	1st to 10th	Night	10% 3 19% 42% 24% 1	570
	11th to 20th	Night	11% 2 18% 44% 23% 4	570
	21st to end	Night	6% 2 21% 43% 26% 2	570
July	1st to 10th	Night	13% 1 13% 35% 31% 7%	555
	11th to 20th	Night	7% 2 15% 39% 33% 4	552
	21st to end	Night	10% 3 12% 41% 31% 3	624
August	1st to 10th	Night	9% 2 14% 35% 37% 4	567
	11th to 20th	Night	9% 1 14% 41% 31% 4	549
	21st to end	Night	6% 1 14% 34% 40% 6%	594
September	1st to 10th	Night	15% 2 13% 31% 34% 4	630
	11th to 20th	Night	10% 3 14% 33% 34% 6%	720
	21st to end	Night	15% 5% 21% 29% 27% 2	720
October	1st to 10th	Night	12% 4 22% 35% 23% 4	720
	11th to 20th	Night	19% 8% 27% 31% 14% 1	720
	21st to end	Night	24% 8% 30% 27% 11%	792
November	1st to 10th	Night	18% 8% 28% 29% 17% 1	740
	11th to 20th	Night	22% 12% 29% 27% 10% 1	760
	21st to end	Night	25% 9% 26% 31% 8% 1	760
December	1st to 10th	Night	27% 11% 30% 25% 6%	760
	11th to 20th	Night	24% 9% 33% 27% 6% 1	760
	21st to end	Night	30% 14% 29% 24% 3	921

Page generated at 2024-08-12 09:52:51. Version ac07

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