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 2026-05-02.

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	14% 9% 3 8% 5% 4 5% 4 6% 7% 35%	131894
	Night	14% 10% 3 8% 5% 4 4 4 5% 7% 36%	130622
Transparency	Day	46% 5% 11% 22% 13% 1	135532
	Night	47% 5% 11% 22% 14% 2	135054
Seeing	Day	18% 12% 26% 22% 15% 6%	17300
	Night	19% 8% 26% 30% 15% 2	27068

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% 16% 7% 11% 4 4 3 3 4 5% 25%	4691
	11th to 20th	Day	11% 14% 6% 15% 6% 5% 4 3 3 5% 27%	5108
	21st to end	Day	19% 13% 6% 10% 7% 6% 5% 4 5% 5% 20%	5780
February	1st to 10th	Day	18% 14% 4 9% 5% 4 4 3 4 6% 29%	1995
	11th to 20th	Day	16% 12% 4 11% 5% 5% 3 3 4 6% 30%	2048
	21st to end	Day	17% 13% 5% 9% 6% 3 4 2 4 5% 32%	1730
March	1st to 10th	Day	18% 14% 5% 10% 5% 4 4 3 4 4 30%	4619
	11th to 20th	Day	13% 9% 3 7% 4 4 4 4 5% 8% 40%	5090
	21st to end	Day	17% 9% 3 8% 4 4 5% 4 5% 7% 33%	5586
April	1st to 10th	Day	15% 11% 3 7% 5% 4 4 4 5% 7% 35%	2478
	11th to 20th	Day	15% 9% 2 8% 4 5% 4 3 5% 7% 38%	2554
	21st to end	Day	17% 8% 3 7% 4 5% 4 4 5% 7% 36%	2730
May	1st to 10th	Day	19% 9% 4 8% 5% 5% 5% 4 5% 8% 28%	5875
	11th to 20th	Day	19% 9% 3 8% 4 3 4 3 5% 7% 35%	5861
	21st to end	Day	13% 7% 3 7% 6% 5% 6% 5% 7% 9% 32%	6433
June	1st to 10th	Day	12% 6% 2 6% 5% 5% 5% 5% 7% 8% 40%	2609
	11th to 20th	Day	9% 5% 3 7% 5% 5% 5% 5% 6% 9% 42%	2800
	21st to end	Day	8% 6% 3 6% 5% 4 6% 5% 6% 10% 40%	2800
July	1st to 10th	Day	9% 6% 2 7% 5% 4 5% 4 7% 10% 40%	6360
	11th to 20th	Day	8% 6% 3 7% 5% 5% 5% 5% 7% 11% 37%	6158
	21st to end	Day	10% 7% 3 8% 6% 6% 7% 5% 7% 9% 31%	6424
August	1st to 10th	Day	8% 5% 2 6% 4 5% 6% 4 8% 9% 43%	4234
	11th to 20th	Day	8% 5% 2 6% 4 5% 5% 5% 7% 10% 42%	4174
	21st to end	Day	6% 4 2 5% 4 3 4 4 6% 9% 53%	4350
September	1st to 10th	Day	12% 5% 2 6% 3 4 4 3 5% 7% 49%	2277
	11th to 20th	Day	8% 5% 2 5% 4 4 4 4 6% 9% 50%	2200
	21st to end	Day	14% 7% 2 5% 4 4 3 3 5% 6% 46%	2200
October	1st to 10th	Day	10% 5% 2 6% 5% 5% 4 3 5% 6% 50%	2200
	11th to 20th	Day	12% 7% 2 6% 4 4 3 3 5% 6% 47%	2030
	21st to end	Day	20% 8% 2 7% 4 3 3 3 5% 6% 38%	2045
November	1st to 10th	Day	9% 7% 3 6% 3 4 4 3 4 6% 51%	1852
	11th to 20th	Day	15% 11% 3 9% 4 4 3 3 6% 7% 36%	1890
	21st to end	Day	18% 11% 4 7% 5% 4 3 3 5% 5% 34%	1890
December	1st to 10th	Day	17% 10% 4 8% 5% 4 4 2 4 5% 36%	3020
	11th to 20th	Day	17% 14% 6% 10% 5% 5% 4 3 5% 5% 26%	3463
	21st to end	Day	21% 20% 5% 11% 5% 4 4 3 4 5% 18%	4340
January	1st to 10th	Night	14% 15% 5% 13% 7% 5% 5% 4 5% 5% 20%	8232
	11th to 20th	Night	11% 16% 7% 15% 7% 5% 5% 3 4 5% 22%	7826
	21st to end	Night	18% 13% 4 8% 5% 5% 4 3 4 5% 31%	8401
February	1st to 10th	Night	19% 12% 4 9% 6% 4 4 4 4 5% 28%	2620
	11th to 20th	Night	16% 11% 4 9% 6% 4 5% 4 5% 6% 30%	2458
	21st to end	Night	20% 13% 4 9% 3 4 4 3 4 6% 30%	2076
March	1st to 10th	Night	20% 13% 3 6% 4 4 3 3 4 5% 37%	5452
	11th to 20th	Night	11% 7% 2 7% 4 4 4 4 5% 7% 42%	5090
	21st to end	Night	16% 9% 4 8% 4 4 5% 4 5% 6% 34%	5588
April	1st to 10th	Night	15% 9% 2 6% 4 4 4 4 5% 7% 37%	2158
	11th to 20th	Night	14% 7% 2 6% 4 4 4 4 7% 8% 40%	2014
	21st to end	Night	16% 7% 2 6% 5% 4 4 4 6% 8% 38%	1890
May	1st to 10th	Night	20% 10% 3 8% 5% 5% 4 4 5% 7% 27%	4042
	11th to 20th	Night	16% 7% 3 7% 5% 4 5% 5% 7% 9% 34%	4032
	21st to end	Night	13% 6% 2 8% 4 4 5% 4 6% 9% 38%	4421
June	1st to 10th	Night	9% 5% 2 5% 5% 4 4 3 5% 9% 49%	1785
	11th to 20th	Night	9% 6% 2 5% 4 5% 4 5% 7% 10% 45%	1600
	21st to end	Night	6% 4 2 5% 5% 4 6% 4 8% 10% 47%	1600
July	1st to 10th	Night	9% 5% 2 6% 4 4 4 4 6% 9% 46%	3618
	11th to 20th	Night	7% 6% 2 7% 5% 4 5% 4 7% 10% 42%	3793
	21st to end	Night	9% 7% 3 6% 5% 5% 5% 5% 7% 10% 39%	4427
August	1st to 10th	Night	7% 7% 2 7% 5% 4 5% 4 6% 8% 44%	2915
	11th to 20th	Night	7% 6% 2 7% 4 5% 5% 4 5% 8% 47%	2875
	21st to end	Night	4 2 2 4 3 4 4 4 6% 10% 57%	3544
September	1st to 10th	Night	12% 5% 1 4 4 3 4 3 5% 6% 52%	2101
	11th to 20th	Night	7% 4 2 5% 3 4 4 4 5% 7% 56%	2200
	21st to end	Night	14% 7% 2 6% 4 3 4 3 4 6% 49%	2200
October	1st to 10th	Night	8% 4 2 6% 4 4 3 3 5% 6% 55%	2200
	11th to 20th	Night	13% 7% 2 6% 4 4 4 3 5% 7% 45%	2370
	21st to end	Night	18% 9% 3 6% 4 4 5% 3 4 5% 40%	2791
November	1st to 10th	Night	13% 8% 2 5% 4 3 4 3 5% 6% 47%	2666
	11th to 20th	Night	16% 9% 3 7% 4 4 3 3 5% 6% 41%	2730
	21st to end	Night	19% 13% 4 8% 5% 4 3 3 4 7% 30%	2730
December	1st to 10th	Night	17% 11% 4 8% 4 4 3 3 4 5% 37%	4380
	11th to 20th	Night	18% 14% 6% 10% 6% 5% 3 3 5% 5% 26%	4952
	21st to end	Night	23% 18% 6% 11% 6% 4 4 3 4 5% 17%	6845

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	62% 3 13% 17% 5%	4692
	11th to 20th	Day	61% 4 9% 14% 11% 1	5108
	21st to end	Day	67% 3 9% 14% 6% 1	5780
February	1st to 10th	Day	57% 5% 11% 18% 9% 1	1995
	11th to 20th	Day	57% 4 10% 19% 9% 1	2058
	21st to end	Day	55% 5% 10% 20% 9% 1	1730
March	1st to 10th	Day	57% 4 6% 19% 12% 2	4619
	11th to 20th	Day	42% 5% 9% 27% 15% 1	5090
	21st to end	Day	49% 5% 12% 20% 11% 2	5586
April	1st to 10th	Day	47% 6% 12% 22% 12% 1	2478
	11th to 20th	Day	45% 5% 11% 22% 14% 3	2554
	21st to end	Day	47% 6% 10% 24% 11% 2	2730
May	1st to 10th	Day	53% 7% 12% 17% 10% 1	5910
	11th to 20th	Day	49% 6% 11% 23% 10%	5865
	21st to end	Day	43% 9% 13% 22% 12% 1	6447
June	1st to 10th	Day	40% 8% 11% 22% 17% 2	2609
	11th to 20th	Day	37% 8% 14% 22% 17% 2	2800
	21st to end	Day	38% 9% 15% 20% 15% 4	2800
July	1st to 10th	Day	39% 4 12% 26% 18% 1	6291
	11th to 20th	Day	40% 5% 15% 26% 14% 1	6083
	21st to end	Day	46% 6% 14% 19% 12% 2	6240
August	1st to 10th	Day	33% 7% 17% 31% 11% 1	4221
	11th to 20th	Day	35% 5% 12% 32% 15% 1	4213
	21st to end	Day	28% 5% 14% 30% 20% 3	4349
September	1st to 10th	Day	33% 6% 11% 24% 20% 5%	2277
	11th to 20th	Day	31% 6% 12% 25% 23% 3	2200
	21st to end	Day	39% 5% 10% 22% 22% 2	2200
October	1st to 10th	Day	24% 4 9% 32% 30% 2	3590
	11th to 20th	Day	30% 3 9% 30% 26% 2	3283
	21st to end	Day	37% 3 10% 25% 23% 2	3282
November	1st to 10th	Day	35% 5% 10% 29% 19% 2	1852
	11th to 20th	Day	48% 4 10% 21% 15% 3	1890
	21st to end	Day	53% 4 10% 21% 12% 1	1890
December	1st to 10th	Day	52% 3 10% 26% 10%	3020
	11th to 20th	Day	61% 5% 9% 18% 7%	3460
	21st to end	Day	69% 4 10% 12% 5%	4340
January	1st to 10th	Night	64% 4 10% 15% 6%	8233
	11th to 20th	Night	65% 3 8% 12% 9% 2	7826
	21st to end	Night	56% 3 11% 21% 9% 1	8401
February	1st to 10th	Night	57% 5% 10% 20% 7% 1	2620
	11th to 20th	Night	54% 5% 10% 20% 10% 1	2459
	21st to end	Night	56% 4 11% 17% 10% 2	2076
March	1st to 10th	Night	50% 4 6% 27% 11% 2	5452
	11th to 20th	Night	39% 6% 12% 27% 15% 1	5090
	21st to end	Night	50% 5% 8% 24% 11% 2	5588
April	1st to 10th	Night	45% 6% 12% 23% 12% 2	2158
	11th to 20th	Night	40% 6% 13% 19% 18% 5%	2014
	21st to end	Night	44% 6% 12% 22% 13% 3	1890
May	1st to 10th	Night	55% 7% 10% 18% 8% 3	4069
	11th to 20th	Night	44% 8% 14% 23% 10% 1	4033
	21st to end	Night	39% 8% 18% 21% 10% 3	4429
June	1st to 10th	Night	32% 8% 10% 26% 21% 2	1785
	11th to 20th	Night	32% 7% 14% 22% 20% 4	1600
	21st to end	Night	30% 8% 17% 21% 18% 5%	1600
July	1st to 10th	Night	35% 5% 11% 25% 19% 4	3580
	11th to 20th	Night	36% 7% 15% 26% 15% 1	3748
	21st to end	Night	39% 5% 14% 25% 15% 3	4297
August	1st to 10th	Night	36% 6% 14% 31% 12% 1	2904
	11th to 20th	Night	35% 6% 12% 29% 18% 1	2902
	21st to end	Night	22% 5% 16% 31% 23% 3	3544
September	1st to 10th	Night	31% 6% 12% 25% 20% 6%	2101
	11th to 20th	Night	28% 6% 10% 25% 28% 3	2200
	21st to end	Night	38% 5% 9% 21% 26% 2	2200
October	1st to 10th	Night	23% 3 7% 28% 37% 3	3590
	11th to 20th	Night	28% 4 9% 26% 32% 2	3856
	21st to end	Night	34% 3 8% 23% 27% 5%	4504
November	1st to 10th	Night	38% 4 11% 22% 22% 3	2666
	11th to 20th	Night	44% 4 9% 23% 17% 3	2730
	21st to end	Night	54% 4 10% 20% 10% 1	2730
December	1st to 10th	Night	51% 4 12% 24% 10%	4380
	11th to 20th	Night	60% 4 11% 18% 7%	4954
	21st to end	Night	70% 4 9% 13% 3	6845

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% 15% 5%	330
	11th to 20th	Day	26% 26% 34% 11% 3	330
	21st to end	Day	30% 21% 30% 15% 3	363
February	1st to 10th	Day	26% 21% 34% 17% 3	330
	11th to 20th	Day	28% 25% 31% 13% 2	330
	21st to end	Day	25% 21% 44% 9% 1	273
March	1st to 10th	Day	26% 24% 35% 13% 3	343
	11th to 20th	Day	26% 17% 33% 17% 6%	540
	21st to end	Day	27% 19% 32% 16% 6%	594
April	1st to 10th	Day	21% 20% 30% 19% 8% 1	540
	11th to 20th	Day	20% 21% 26% 20% 10% 3	532
	21st to end	Day	20% 16% 32% 19% 10% 2	540
May	1st to 10th	Day	23% 14% 32% 19% 9% 4	507
	11th to 20th	Day	22% 10% 27% 22% 13% 6%	527
	21st to end	Day	14% 8% 23% 28% 16% 10%	573
June	1st to 10th	Day	14% 7% 23% 29% 19% 8%	539
	11th to 20th	Day	11% 6% 23% 32% 23% 6%	730
	21st to end	Day	10% 7% 23% 32% 19% 9%	730
July	1st to 10th	Day	13% 3 17% 26% 25% 16%	721
	11th to 20th	Day	9% 4 23% 26% 26% 11%	633
	21st to end	Day	12% 2 17% 28% 26% 15%	576
August	1st to 10th	Day	9% 4 17% 25% 27% 18%	526
	11th to 20th	Day	11% 4 19% 27% 25% 14%	519
	21st to end	Day	11% 2 14% 29% 30% 14%	583
September	1st to 10th	Day	11% 5% 17% 24% 32% 11%	530
	11th to 20th	Day	9% 3 13% 25% 34% 16%	530
	21st to end	Day	17% 8% 22% 23% 20% 10%	530
October	1st to 10th	Day	10% 6% 22% 30% 24% 8%	530
	11th to 20th	Day	15% 13% 29% 25% 14% 4	530
	21st to end	Day	24% 14% 32% 23% 6%	428
November	1st to 10th	Day	12% 14% 37% 23% 11% 3	330
	11th to 20th	Day	24% 19% 28% 19% 7% 2	330
	21st to end	Day	26% 14% 39% 17% 4	330
December	1st to 10th	Day	20% 20% 38% 15% 5% 1	330
	11th to 20th	Day	22% 20% 39% 13% 6%	330
	21st to end	Day	32% 17% 32% 16% 3 1	363
January	1st to 10th	Night	22% 17% 31% 25% 6%	1050
	11th to 20th	Night	27% 15% 34% 21% 3	895
	21st to end	Night	23% 14% 34% 26% 3	924
February	1st to 10th	Night	28% 10% 31% 28% 2	840
	11th to 20th	Night	23% 15% 35% 23% 3	823
	21st to end	Night	27% 14% 32% 25% 2	692
March	1st to 10th	Night	23% 12% 35% 26% 5%	840
	11th to 20th	Night	22% 13% 33% 25% 6%	840
	21st to end	Night	22% 14% 30% 28% 6%	924
April	1st to 10th	Night	19% 12% 36% 25% 8%	688
	11th to 20th	Night	19% 10% 32% 29% 10% 1	623
	21st to end	Night	18% 8% 36% 28% 9% 1	630
May	1st to 10th	Night	23% 8% 28% 28% 12% 1	603
	11th to 20th	Night	18% 4 25% 33% 18% 2	591
	21st to end	Night	10% 3 24% 34% 26% 3	650
June	1st to 10th	Night	10% 3 20% 42% 24% 1	600
	11th to 20th	Night	12% 2 17% 43% 23% 4	600
	21st to end	Night	6% 2 20% 42% 28% 3	600
July	1st to 10th	Night	12% 2 13% 35% 31% 7%	585
	11th to 20th	Night	7% 2 15% 38% 34% 4	582
	21st to end	Night	10% 3 12% 40% 32% 3	657
August	1st to 10th	Night	8% 2 14% 36% 36% 4	597
	11th to 20th	Night	8% 1 13% 41% 31% 5%	594
	21st to end	Night	6% 1 14% 34% 39% 6%	660
September	1st to 10th	Night	14% 2 14% 32% 34% 4	701
	11th to 20th	Night	10% 3 13% 34% 36% 6%	800
	21st to end	Night	17% 5% 21% 29% 27% 2	800
October	1st to 10th	Night	11% 4 21% 35% 24% 4	800
	11th to 20th	Night	18% 8% 26% 32% 15% 1	800
	21st to end	Night	23% 9% 31% 27% 11%	880
November	1st to 10th	Night	17% 9% 29% 29% 16% 1	820
	11th to 20th	Night	21% 13% 29% 27% 10%	840
	21st to end	Night	26% 10% 25% 30% 7% 1	840
December	1st to 10th	Night	27% 11% 31% 25% 6%	840
	11th to 20th	Night	24% 10% 33% 27% 5% 1	840
	21st to end	Night	31% 14% 29% 23% 3	1019

Page generated at 2026-04-29 02:21:45. Version ac07

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