Lilly Bluff Overlook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lilly Bluff Overlook clear sky chart from 2005-11-06 to 2026-04-02.

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	13% 8% 3 8% 5% 5% 5% 4 6% 7% 36%	131340
	Night	13% 8% 3 7% 5% 4 4 4 5% 7% 40%	130518
Transparency	Day	43% 7% 11% 21% 15% 3	135066
	Night	41% 7% 12% 22% 16% 4	134861
Seeing	Day	18% 14% 25% 22% 15% 7%	16539
	Night	16% 12% 23% 28% 18% 3	26659

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	17% 12% 5% 10% 4 4 5% 4 4 5% 31%	5258
	11th to 20th	Day	12% 8% 5% 12% 3 4 3 2 4 4 42%	5280
	21st to end	Day	19% 11% 5% 7% 5% 4 3 3 4 5% 34%	5880
February	1st to 10th	Day	17% 11% 4 8% 5% 4 4 3 4 5% 34%	2100
	11th to 20th	Day	21% 10% 4 8% 5% 5% 4 3 4 5% 31%	2048
	21st to end	Day	19% 9% 4 8% 5% 4 4 3 4 5% 36%	1730
March	1st to 10th	Day	18% 11% 4 8% 5% 4 5% 3 5% 6% 32%	4623
	11th to 20th	Day	12% 8% 3 6% 4 4 4 3 4 5% 46%	5090
	21st to end	Day	13% 8% 3 6% 4 5% 4 4 4 6% 42%	5586
April	1st to 10th	Day	13% 9% 2 7% 4 5% 4 3 6% 6% 40%	2350
	11th to 20th	Day	14% 8% 3 6% 5% 3 4 3 5% 7% 43%	2374
	21st to end	Day	13% 8% 2 7% 5% 5% 5% 4 5% 7% 40%	2577
May	1st to 10th	Day	18% 10% 3 9% 5% 5% 6% 5% 7% 8% 26%	5862
	11th to 20th	Day	14% 10% 3 10% 6% 6% 5% 4 7% 7% 28%	5861
	21st to end	Day	14% 9% 3 8% 5% 4 4 4 6% 7% 36%	6433
June	1st to 10th	Day	10% 7% 3 7% 4 6% 6% 5% 8% 9% 35%	2600
	11th to 20th	Day	5% 5% 2 7% 6% 6% 6% 6% 8% 10% 39%	2600
	21st to end	Day	6% 5% 2 6% 6% 6% 6% 5% 8% 11% 38%	2600
July	1st to 10th	Day	6% 5% 2 7% 6% 7% 7% 6% 7% 10% 37%	5900
	11th to 20th	Day	8% 7% 3 9% 7% 7% 7% 7% 8% 10% 27%	5900
	21st to end	Day	11% 10% 4 10% 7% 7% 7% 5% 8% 9% 21%	6424
August	1st to 10th	Day	7% 5% 3 7% 5% 6% 6% 5% 8% 11% 37%	4234
	11th to 20th	Day	7% 5% 2 7% 5% 6% 6% 6% 9% 12% 35%	3980
	21st to end	Day	6% 4 2 6% 4 5% 6% 4 7% 9% 47%	4312
September	1st to 10th	Day	13% 6% 3 7% 5% 5% 5% 4 6% 7% 39%	2257
	11th to 20th	Day	13% 6% 2 7% 4 5% 6% 3 6% 8% 41%	2200
	21st to end	Day	15% 5% 2 5% 5% 5% 5% 4 5% 7% 43%	2200
October	1st to 10th	Day	11% 5% 2 6% 4 3 3 4 5% 6% 52%	2200
	11th to 20th	Day	12% 5% 2 5% 3 2 3 2 5% 6% 54%	2087
	21st to end	Day	15% 6% 2 5% 3 3 3 3 5% 7% 47%	2114
November	1st to 10th	Day	10% 6% 3 5% 4 3 4 4 6% 5% 53%	1852
	11th to 20th	Day	12% 7% 2 6% 4 3 4 3 6% 6% 47%	1890
	21st to end	Day	15% 8% 3 6% 4 5% 4 3 5% 5% 42%	1890
December	1st to 10th	Day	12% 10% 3 9% 5% 4 5% 2 4 5% 40%	3020
	11th to 20th	Day	17% 14% 5% 9% 5% 4 4 3 5% 5% 29%	3463
	21st to end	Day	16% 13% 5% 8% 4 4 5% 3 5% 7% 30%	4565
January	1st to 10th	Night	14% 11% 4 9% 4 3 3 3 5% 6% 38%	7635
	11th to 20th	Night	16% 9% 3 7% 5% 5% 3 3 4 4 42%	7680
	21st to end	Night	18% 13% 3 7% 4 4 4 4 4 4 37%	8299
February	1st to 10th	Night	17% 8% 3 8% 5% 4 5% 4 5% 7% 34%	2520
	11th to 20th	Night	22% 10% 4 8% 5% 4 4 3 4 5% 32%	2458
	21st to end	Night	20% 9% 3 8% 5% 5% 5% 4 4 5% 32%	2076
March	1st to 10th	Night	16% 13% 4 7% 5% 5% 4 3 5% 6% 33%	5447
	11th to 20th	Night	10% 7% 2 5% 4 4 3 4 6% 6% 49%	5090
	21st to end	Night	14% 8% 3 7% 4 5% 5% 4 5% 6% 40%	5588
April	1st to 10th	Night	13% 5% 2 5% 4 5% 4 4 6% 8% 44%	2089
	11th to 20th	Night	12% 6% 2 6% 4 4 4 3 5% 6% 48%	1975
	21st to end	Night	11% 6% 2 7% 5% 5% 4 4 5% 7% 44%	1821
May	1st to 10th	Night	14% 10% 3 8% 6% 5% 5% 4 7% 9% 30%	4033
	11th to 20th	Night	15% 10% 4 9% 6% 5% 5% 4 6% 6% 29%	4032
	21st to end	Night	12% 7% 3 8% 6% 5% 5% 4 6% 8% 37%	4421
June	1st to 10th	Night	6% 6% 2 6% 5% 5% 6% 6% 7% 9% 43%	1800
	11th to 20th	Night	4 3 2 6% 4 5% 4 5% 7% 12% 50%	1800
	21st to end	Night	6% 5% 2 6% 6% 5% 5% 4 7% 12% 43%	1800
July	1st to 10th	Night	7% 5% 2 6% 5% 5% 5% 5% 8% 10% 42%	4058
	11th to 20th	Night	8% 5% 2 7% 5% 5% 6% 5% 7% 12% 39%	4057
	21st to end	Night	9% 9% 3 10% 6% 6% 6% 5% 8% 13% 26%	4427
August	1st to 10th	Night	5% 5% 2 6% 5% 5% 4 4 7% 10% 47%	2915
	11th to 20th	Night	6% 6% 2 6% 5% 5% 3 4 7% 9% 47%	3065
	21st to end	Night	6% 3 1 4 3 4 4 4 6% 8% 59%	3586
September	1st to 10th	Night	10% 6% 2 7% 5% 5% 5% 3 5% 7% 45%	2121
	11th to 20th	Night	10% 6% 2 7% 4 4 4 4 5% 8% 46%	2200
	21st to end	Night	12% 6% 2 6% 4 4 4 3 5% 6% 51%	2200
October	1st to 10th	Night	10% 5% 1 5% 3 3 3 2 4 7% 57%	2200
	11th to 20th	Night	12% 5% 2 5% 3 3 3 3 4 6% 53%	2311
	21st to end	Night	13% 7% 3 6% 3 3 3 2 3 6% 50%	2723
November	1st to 10th	Night	10% 6% 3 6% 4 3 3 3 4 6% 51%	2666
	11th to 20th	Night	11% 8% 2 5% 4 3 5% 3 4 7% 47%	2730
	21st to end	Night	14% 10% 4 6% 4 3 4 4 4 6% 42%	2730
December	1st to 10th	Night	16% 10% 4 9% 5% 4 4 3 4 4 37%	4380
	11th to 20th	Night	17% 14% 6% 8% 4 3 3 2 4 5% 33%	4952
	21st to end	Night	15% 11% 6% 7% 5% 5% 5% 4 6% 7% 29%	6633

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	53% 5% 10% 20% 11% 1	5259
	11th to 20th	Day	44% 4 5% 19% 25% 3	5280
	21st to end	Day	51% 4 8% 22% 13% 2	5880
February	1st to 10th	Day	52% 5% 8% 18% 16% 2	2100
	11th to 20th	Day	55% 4 7% 18% 13% 3	2058
	21st to end	Day	50% 5% 8% 16% 16% 5%	1730
March	1st to 10th	Day	52% 5% 7% 13% 14% 8%	4623
	11th to 20th	Day	40% 4 7% 22% 18% 8%	5090
	21st to end	Day	42% 5% 9% 28% 15% 1	5586
April	1st to 10th	Day	43% 6% 12% 22% 16% 3	2350
	11th to 20th	Day	41% 5% 9% 18% 24% 3	2374
	21st to end	Day	43% 7% 12% 25% 13% 1	2577
May	1st to 10th	Day	53% 9% 11% 18% 8% 1	5897
	11th to 20th	Day	52% 10% 12% 18% 7%	5865
	21st to end	Day	45% 8% 11% 20% 14% 3	6447
June	1st to 10th	Day	41% 10% 15% 19% 13% 2	2600
	11th to 20th	Day	36% 11% 17% 20% 14% 2	2600
	21st to end	Day	36% 11% 18% 19% 13% 4	2600
July	1st to 10th	Day	36% 13% 16% 20% 14% 1	5835
	11th to 20th	Day	45% 14% 18% 18% 4 1	5831
	21st to end	Day	53% 12% 14% 16% 4	6240
August	1st to 10th	Day	34% 12% 16% 28% 9%	4221
	11th to 20th	Day	34% 11% 18% 23% 13% 1	4019
	21st to end	Day	29% 10% 14% 35% 12% 2	4311
September	1st to 10th	Day	42% 8% 12% 18% 17% 5%	2257
	11th to 20th	Day	39% 8% 13% 22% 16% 2	2200
	21st to end	Day	39% 7% 10% 22% 18% 5%	2200
October	1st to 10th	Day	22% 7% 8% 20% 32% 11%	3590
	11th to 20th	Day	23% 3 8% 24% 30% 11%	3379
	21st to end	Day	29% 4 11% 25% 22% 10%	3390
November	1st to 10th	Day	33% 5% 8% 23% 26% 5%	1852
	11th to 20th	Day	38% 4 7% 23% 23% 5%	1890
	21st to end	Day	43% 4 9% 22% 20% 3	1890
December	1st to 10th	Day	45% 5% 5% 21% 23% 2	3020
	11th to 20th	Day	57% 4 9% 17% 12% 2	3460
	21st to end	Day	52% 5% 13% 19% 9% 1	4565
January	1st to 10th	Night	45% 5% 16% 22% 12% 1	7636
	11th to 20th	Night	44% 4 6% 19% 23% 4	7680
	21st to end	Night	49% 4 8% 17% 15% 6%	8299
February	1st to 10th	Night	49% 5% 11% 20% 15% 2	2520
	11th to 20th	Night	54% 4 7% 18% 12% 4	2459
	21st to end	Night	53% 5% 6% 17% 15% 4	2076
March	1st to 10th	Night	50% 5% 10% 15% 16% 4	5447
	11th to 20th	Night	34% 5% 7% 24% 20% 10%	5090
	21st to end	Night	44% 5% 10% 27% 13% 2	5588
April	1st to 10th	Night	37% 6% 12% 24% 19% 3	2089
	11th to 20th	Night	36% 5% 10% 21% 22% 6%	1975
	21st to end	Night	39% 7% 12% 28% 13% 1	1821
May	1st to 10th	Night	48% 9% 14% 21% 7% 1	4060
	11th to 20th	Night	52% 9% 13% 16% 9%	4033
	21st to end	Night	42% 10% 13% 22% 13% 1	4429
June	1st to 10th	Night	35% 10% 15% 25% 13% 2	1800
	11th to 20th	Night	26% 10% 21% 27% 15% 2	1800
	21st to end	Night	33% 11% 14% 24% 14% 4	1800
July	1st to 10th	Night	34% 12% 20% 22% 12% 1	4015
	11th to 20th	Night	35% 11% 24% 23% 6% 2	4006
	21st to end	Night	46% 13% 19% 16% 5% 1	4297
August	1st to 10th	Night	29% 10% 16% 32% 12% 1	2904
	11th to 20th	Night	29% 12% 20% 26% 12% 1	3092
	21st to end	Night	23% 7% 13% 41% 15% 1	3586
September	1st to 10th	Night	37% 8% 13% 19% 18% 6%	2121
	11th to 20th	Night	35% 9% 12% 22% 21% 2	2200
	21st to end	Night	35% 7% 9% 22% 22% 4	2200
October	1st to 10th	Night	22% 7% 9% 21% 29% 11%	3590
	11th to 20th	Night	21% 4 7% 25% 28% 15%	3758
	21st to end	Night	26% 3 9% 24% 27% 11%	4397
November	1st to 10th	Night	34% 5% 8% 22% 23% 7%	2666
	11th to 20th	Night	36% 5% 8% 21% 23% 7%	2730
	21st to end	Night	43% 3 7% 24% 19% 4	2730
December	1st to 10th	Night	48% 6% 7% 17% 21% 2	4380
	11th to 20th	Night	53% 4 8% 20% 14% 2	4954
	21st to end	Night	52% 6% 14% 18% 9%	6633

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	28% 28% 29% 13% 1	330
	11th to 20th	Day	33% 29% 24% 11% 2 1	330
	21st to end	Day	26% 29% 33% 9% 2	363
February	1st to 10th	Day	29% 27% 31% 11% 1	330
	11th to 20th	Day	42% 26% 26% 4 1 1	330
	21st to end	Day	38% 24% 29% 8% 1	273
March	1st to 10th	Day	29% 24% 34% 12% 1	347
	11th to 20th	Day	27% 27% 27% 15% 4	540
	21st to end	Day	24% 23% 33% 15% 5%	594
April	1st to 10th	Day	26% 21% 25% 19% 9% 1	504
	11th to 20th	Day	20% 20% 33% 18% 9% 1	492
	21st to end	Day	21% 14% 33% 19% 12% 1	500
May	1st to 10th	Day	19% 18% 33% 17% 8% 4	503
	11th to 20th	Day	15% 12% 27% 26% 13% 7%	527
	21st to end	Day	16% 11% 21% 27% 15% 10%	573
June	1st to 10th	Day	11% 9% 24% 28% 17% 11%	530
	11th to 20th	Day	5% 6% 18% 32% 27% 13%	530
	21st to end	Day	7% 5% 22% 28% 23% 14%	530
July	1st to 10th	Day	9% 4 16% 28% 25% 18%	525
	11th to 20th	Day	9% 6% 15% 26% 26% 18%	524
	21st to end	Day	11% 6% 13% 24% 31% 14%	576
August	1st to 10th	Day	13% 5% 18% 27% 23% 14%	526
	11th to 20th	Day	10% 4 18% 30% 26% 11%	519
	21st to end	Day	10% 5% 11% 27% 30% 17%	583
September	1st to 10th	Day	10% 5% 15% 28% 29% 12%	530
	11th to 20th	Day	13% 4 13% 29% 29% 12%	530
	21st to end	Day	17% 5% 19% 28% 23% 7%	530
October	1st to 10th	Day	11% 10% 21% 26% 23% 8%	530
	11th to 20th	Day	15% 13% 28% 25% 17% 3	530
	21st to end	Day	21% 14% 30% 23% 12% 1	497
November	1st to 10th	Day	17% 14% 37% 24% 7% 2	330
	11th to 20th	Day	18% 19% 39% 21% 3	330
	21st to end	Day	20% 21% 37% 16% 5% 1	330
December	1st to 10th	Day	29% 23% 34% 11% 3	330
	11th to 20th	Day	27% 23% 30% 15% 5%	330
	21st to end	Day	31% 23% 31% 12% 2 1	363
January	1st to 10th	Night	22% 23% 31% 20% 4	840
	11th to 20th	Night	26% 23% 28% 19% 4	840
	21st to end	Night	21% 18% 37% 21% 2	924
February	1st to 10th	Night	22% 17% 34% 24% 3	840
	11th to 20th	Night	29% 20% 32% 17% 1	823
	21st to end	Night	27% 23% 30% 18% 1	692
March	1st to 10th	Night	20% 17% 34% 25% 3	840
	11th to 20th	Night	20% 20% 31% 23% 5% 1	840
	21st to end	Night	22% 15% 31% 25% 7%	924
April	1st to 10th	Night	17% 19% 27% 27% 10%	682
	11th to 20th	Night	16% 12% 31% 29% 11% 1	593
	21st to end	Night	13% 11% 32% 34% 10% 1	600
May	1st to 10th	Night	13% 11% 28% 32% 15% 2	600
	11th to 20th	Night	11% 9% 21% 34% 20% 4	591
	21st to end	Night	8% 4 19% 33% 30% 5%	650
June	1st to 10th	Night	7% 7% 14% 38% 29% 5%	600
	11th to 20th	Night	4 3 15% 36% 37% 6%	600
	21st to end	Night	6% 3 11% 38% 33% 9%	600
July	1st to 10th	Night	10% 3 6% 31% 41% 9%	585
	11th to 20th	Night	7% 4 8% 26% 45% 10%	582
	21st to end	Night	7% 2 9% 30% 41% 10%	657
August	1st to 10th	Night	8% 3 9% 29% 44% 8%	597
	11th to 20th	Night	7% 4 11% 33% 41% 5%	594
	21st to end	Night	10% 2 7% 30% 40% 11%	660
September	1st to 10th	Night	9% 3 12% 33% 36% 8%	721
	11th to 20th	Night	12% 3 11% 31% 35% 8%	800
	21st to end	Night	14% 4 17% 30% 31% 4	800
October	1st to 10th	Night	12% 7% 17% 27% 30% 7%	800
	11th to 20th	Night	15% 9% 24% 32% 19% 2	800
	21st to end	Night	15% 12% 27% 30% 14% 2	880
November	1st to 10th	Night	13% 12% 21% 36% 16% 2	820
	11th to 20th	Night	14% 18% 29% 28% 10% 1	840
	21st to end	Night	19% 18% 26% 27% 10%	840
December	1st to 10th	Night	24% 19% 28% 24% 5%	840
	11th to 20th	Night	21% 17% 28% 27% 6%	840
	21st to end	Night	26% 17% 27% 25% 5%	924

Page generated at 2026-03-30 02:18:44. Version ac07

Copyright © 2026 Attilla Danko.