Lava Springs Star Party
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lava Springs Star Party clear sky chart from 2005-11-06 to 2026-02-16.

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	6% 10% 3 7% 4 4 4 3 5% 6% 50%	139838
	Night	6% 10% 3 7% 4 4 4 3 5% 6% 47%	138382
Transparency	Day	35% 5% 10% 21% 19% 11%	134549
	Night	37% 5% 11% 21% 17% 9%	134674
Seeing	Day	12% 13% 26% 28% 16% 5%	16896
	Night	12% 6% 20% 40% 20% 2	26715

By Month

Percentage Cloud Cover SW (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	6% 28% 8% 11% 3 3 3 3 4 5% 26%	4722
	11th to 20th	Day	4 14% 6% 13% 5% 3 2 2 3 4 44%	5200
	21st to end	Day	6% 16% 4 9% 4 4 3 3 4 5% 42%	5844
February	1st to 10th	Day	10% 18% 7% 11% 4 5% 4 4 5% 5% 27%	1890
	11th to 20th	Day	9% 19% 6% 12% 5% 4 4 3 4 5% 28%	1836
	21st to end	Day	7% 19% 7% 14% 5% 4 5% 3 4 5% 27%	1650
March	1st to 10th	Day	6% 20% 6% 10% 5% 4 4 2 4 4 35%	4772
	11th to 20th	Day	6% 14% 6% 7% 4 4 4 3 5% 6% 40%	5000
	21st to end	Day	8% 20% 5% 10% 6% 6% 6% 4 5% 7% 24%	5486
April	1st to 10th	Day	11% 13% 4 8% 5% 4 4 4 5% 6% 34%	2244
	11th to 20th	Day	9% 13% 3 7% 6% 4 5% 4 5% 6% 38%	2567
	21st to end	Day	9% 12% 3 8% 5% 5% 4 4 7% 7% 37%	2600
May	1st to 10th	Day	8% 11% 2 5% 4 4 3 4 5% 6% 48%	5880
	11th to 20th	Day	7% 7% 2 7% 5% 5% 4 4 6% 7% 46%	5841
	21st to end	Day	6% 5% 2 6% 4 4 4 4 5% 6% 54%	6671
June	1st to 10th	Day	7% 5% 2 5% 4 4 5% 4 6% 8% 51%	2840
	11th to 20th	Day	7% 5% 2 5% 3 3 4 3 5% 8% 53%	3000
	21st to end	Day	3 2 1 3 3 3 3 3 4 6% 69%	3000
July	1st to 10th	Day	2 2 1 3 2 2 3 3 5% 5% 74%	6488
	11th to 20th	Day	1 2 1 4 3 3 4 3 5% 5% 69%	6110
	21st to end	Day	3 2 1 4 3 3 3 3 5% 6% 67%	6401
August	1st to 10th	Day	3 3 1 4 3 3 4 3 5% 6% 64%	5779
	11th to 20th	Day	3 1 1 3 3 3 4 3 5% 6% 67%	5798
	21st to end	Day	4 3 2 4 3 3 3 3 5% 7% 64%	6468
September	1st to 10th	Day	5% 3 1 4 3 3 3 4 4 6% 65%	2292
	11th to 20th	Day	5% 3 1 4 3 3 3 4 5% 7% 62%	2200
	21st to end	Day	8% 4 1 4 3 3 3 2 4 5% 65%	2200
October	1st to 10th	Day	7% 4 1 3 2 3 2 3 4 5% 65%	3421
	11th to 20th	Day	5% 7% 2 6% 3 3 4 2 4 6% 58%	3250
	21st to end	Day	5% 11% 3 6% 4 3 4 3 6% 8% 47%	3425
November	1st to 10th	Day	10% 12% 4 8% 5% 4 4 3 4 6% 40%	1854
	11th to 20th	Day	10% 13% 4 6% 4 3 4 4 5% 7% 39%	1816
	21st to end	Day	6% 14% 5% 8% 4 4 3 4 4 6% 41%	1680
December	1st to 10th	Day	6% 11% 4 8% 4 2 2 2 3 4 54%	2700
	11th to 20th	Day	8% 18% 5% 12% 5% 6% 5% 4 7% 8% 23%	3106
	21st to end	Day	9% 17% 6% 16% 4 5% 6% 4 4 7% 23%	3807
January	1st to 10th	Night	6% 19% 8% 16% 5% 4 4 3 5% 6% 25%	8172
	11th to 20th	Night	5% 14% 5% 12% 4 3 3 2 4 5% 43%	7751
	21st to end	Night	5% 15% 6% 8% 4 4 4 3 4 5% 42%	8370
February	1st to 10th	Night	8% 16% 4 13% 6% 4 5% 4 6% 6% 28%	2730
	11th to 20th	Night	8% 17% 5% 9% 5% 4 4 4 5% 7% 35%	2557
	21st to end	Night	6% 16% 6% 12% 4 3 4 3 5% 6% 33%	1980
March	1st to 10th	Night	7% 19% 4 7% 4 4 4 3 5% 6% 36%	5122
	11th to 20th	Night	5% 12% 3 7% 5% 5% 5% 4 6% 8% 41%	5000
	21st to end	Night	7% 12% 3 7% 5% 5% 5% 4 6% 7% 37%	5489
April	1st to 10th	Night	8% 13% 3 6% 4 4 4 4 6% 6% 42%	2150
	11th to 20th	Night	9% 12% 4 7% 5% 4 4 3 4 6% 43%	1781
	21st to end	Night	8% 8% 2 7% 4 3 4 4 6% 5% 48%	1800
May	1st to 10th	Night	6% 10% 2 6% 4 4 3 3 5% 6% 51%	4100
	11th to 20th	Night	7% 5% 2 5% 4 5% 4 4 6% 8% 49%	4074
	21st to end	Night	6% 4 1 5% 3 4 4 4 7% 8% 56%	4208
June	1st to 10th	Night	5% 4 2 5% 4 4 4 5% 7% 8% 51%	1554
	11th to 20th	Night	8% 4 1 4 3 3 4 3 6% 7% 57%	1400
	21st to end	Night	4 2 1 3 2 2 3 3 4 7% 69%	1400
July	1st to 10th	Night	2 2 1 4 3 3 3 3 5% 4 71%	3452
	11th to 20th	Night	1 2 1 3 3 3 4 4 5% 6% 68%	3842
	21st to end	Night	2 1 1 4 3 3 3 3 5% 8% 67%	4472
August	1st to 10th	Night	3 2 1 3 3 4 4 4 6% 8% 61%	4033
	11th to 20th	Night	3 2 1 4 3 4 5% 3 5% 6% 65%	4051
	21st to end	Night	4 3 1 5% 3 3 4 3 4 5% 64%	4509
September	1st to 10th	Night	3 3 1 3 3 3 3 3 4 5% 69%	2103
	11th to 20th	Night	6% 3 1 4 3 3 3 3 4 6% 64%	2200
	21st to end	Night	7% 3 1 4 3 3 3 2 4 5% 66%	2200
October	1st to 10th	Night	6% 4 1 3 2 2 2 2 4 5% 70%	3760
	11th to 20th	Night	9% 7% 2 5% 3 3 3 3 4 6% 54%	3898
	21st to end	Night	6% 10% 2 6% 3 4 4 4 5% 6% 50%	4372
November	1st to 10th	Night	10% 9% 3 6% 4 4 4 5% 4 6% 44%	2665
	11th to 20th	Night	8% 10% 4 7% 5% 4 4 4 6% 6% 41%	2781
	21st to end	Night	6% 11% 4 9% 5% 4 5% 3 6% 6% 40%	2940
December	1st to 10th	Night	6% 11% 3 8% 4 3 3 3 4 5% 51%	4710
	11th to 20th	Night	9% 16% 5% 10% 5% 5% 4 3 5% 7% 32%	5321
	21st to end	Night	9% 17% 7% 12% 5% 4 5% 4 6% 6% 24%	7435

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% 4 17% 11% 6%	4723
	11th to 20th	Day	46% 4 14% 21% 9% 5%	5200
	21st to end	Day	45% 6% 11% 20% 15% 2	5844
February	1st to 10th	Day	58% 7% 12% 16% 6% 1	1890
	11th to 20th	Day	59% 4 14% 15% 7% 1	1845
	21st to end	Day	59% 5% 12% 15% 8% 2	1650
March	1st to 10th	Day	54% 4 8% 21% 9% 4	4772
	11th to 20th	Day	44% 4 10% 30% 12%	5000
	21st to end	Day	57% 7% 13% 19% 4	5486
April	1st to 10th	Day	50% 6% 12% 18% 12% 2	2244
	11th to 20th	Day	45% 5% 10% 23% 14% 2	2570
	21st to end	Day	44% 6% 11% 25% 14% 1	2600
May	1st to 10th	Day	34% 5% 10% 27% 20% 4	5880
	11th to 20th	Day	34% 5% 9% 31% 18% 3	5844
	21st to end	Day	28% 6% 7% 33% 25% 2	6672
June	1st to 10th	Day	30% 6% 12% 28% 21% 2	2840
	11th to 20th	Day	28% 5% 10% 22% 26% 9%	3000
	21st to end	Day	16% 3 6% 20% 37% 18%	3000
July	1st to 10th	Day	12% 3 4 12% 24% 45%	6420
	11th to 20th	Day	15% 3 3 10% 29% 39%	6035
	21st to end	Day	17% 4 3 11% 33% 32%	6217
August	1st to 10th	Day	20% 5% 5% 16% 30% 24%	4208
	11th to 20th	Day	16% 4 6% 16% 37% 21%	4197
	21st to end	Day	15% 2 6% 18% 32% 27%	4663
September	1st to 10th	Day	20% 4 8% 17% 31% 21%	2292
	11th to 20th	Day	21% 5% 8% 23% 29% 15%	2200
	21st to end	Day	23% 3 8% 24% 33% 8%	2200
October	1st to 10th	Day	23% 3 6% 17% 33% 17%	3421
	11th to 20th	Day	29% 4 7% 34% 20% 7%	3250
	21st to end	Day	34% 5% 16% 28% 16% 1	3425
November	1st to 10th	Day	45% 6% 14% 23% 11% 2	1854
	11th to 20th	Day	44% 6% 18% 22% 9% 1	1816
	21st to end	Day	45% 5% 16% 22% 10% 1	1680
December	1st to 10th	Day	37% 5% 17% 31% 9% 2	2700
	11th to 20th	Day	58% 7% 14% 18% 3	3104
	21st to end	Day	60% 5% 15% 13% 6%	3807
January	1st to 10th	Night	59% 6% 11% 19% 5%	8172
	11th to 20th	Night	45% 4 13% 28% 7% 2	7751
	21st to end	Night	44% 6% 11% 18% 18% 3	8370
February	1st to 10th	Night	54% 7% 15% 18% 6%	2730
	11th to 20th	Night	50% 6% 15% 19% 10% 1	2558
	21st to end	Night	52% 4 14% 20% 7% 3	1980
March	1st to 10th	Night	46% 6% 10% 21% 10% 7%	5122
	11th to 20th	Night	39% 6% 14% 24% 17% 1	5000
	21st to end	Night	41% 9% 17% 24% 8%	5489
April	1st to 10th	Night	41% 6% 14% 19% 15% 4	2150
	11th to 20th	Night	42% 4 13% 22% 16% 2	1781
	21st to end	Night	36% 5% 13% 27% 19%	1800
May	1st to 10th	Night	32% 5% 11% 25% 23% 5%	4097
	11th to 20th	Night	30% 5% 10% 29% 21% 5%	4075
	21st to end	Night	23% 6% 9% 28% 28% 5%	4208
June	1st to 10th	Night	27% 7% 14% 24% 24% 3	1554
	11th to 20th	Night	25% 6% 10% 24% 25% 12%	1400
	21st to end	Night	16% 3 5% 18% 32% 26%	1400
July	1st to 10th	Night	17% 2 3 11% 19% 47%	3412
	11th to 20th	Night	15% 4 3 9% 27% 43%	3794
	21st to end	Night	15% 3 3 10% 33% 35%	4344
August	1st to 10th	Night	19% 5% 5% 12% 25% 33%	2928
	11th to 20th	Night	22% 3 5% 13% 35% 22%	2928
	21st to end	Night	16% 3 5% 16% 33% 28%	3245
September	1st to 10th	Night	18% 2 8% 14% 28% 29%	2103
	11th to 20th	Night	21% 4 8% 22% 27% 18%	2200
	21st to end	Night	23% 4 6% 23% 35% 11%	2200
October	1st to 10th	Night	19% 3 7% 17% 37% 17%	3760
	11th to 20th	Night	32% 3 7% 30% 19% 8%	3898
	21st to end	Night	34% 4 10% 31% 18% 3	4372
November	1st to 10th	Night	39% 5% 13% 24% 16% 2	2665
	11th to 20th	Night	41% 5% 18% 24% 11% 1	2781
	21st to end	Night	44% 5% 15% 24% 10% 2	2940
December	1st to 10th	Night	37% 5% 14% 35% 8% 1	4710
	11th to 20th	Night	53% 7% 17% 18% 5%	5322
	21st to end	Night	58% 5% 15% 15% 7%	7435

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	26% 18% 20% 20% 13% 4	220
	11th to 20th	Day	12% 12% 30% 26% 17% 3	305
	21st to end	Day	13% 12% 27% 31% 14% 2	363
February	1st to 10th	Day	24% 17% 26% 24% 9%	330
	11th to 20th	Day	20% 18% 30% 22% 7% 3	351
	21st to end	Day	14% 22% 32% 23% 9% 1	414
March	1st to 10th	Day	17% 19% 33% 23% 6% 1	500
	11th to 20th	Day	14% 20% 31% 24% 8% 3	500
	21st to end	Day	20% 25% 31% 18% 7%	550
April	1st to 10th	Day	22% 20% 25% 23% 9% 2	500
	11th to 20th	Day	18% 24% 30% 18% 8% 2	492
	21st to end	Day	15% 21% 29% 21% 10% 4	500
May	1st to 10th	Day	11% 19% 30% 28% 9% 3	503
	11th to 20th	Day	16% 14% 29% 26% 12% 3	528
	21st to end	Day	12% 10% 24% 27% 20% 7%	678
June	1st to 10th	Day	7% 10% 23% 31% 24% 5%	730
	11th to 20th	Day	10% 13% 26% 32% 16% 2	730
	21st to end	Day	4 6% 24% 35% 24% 7%	730
July	1st to 10th	Day	4 5% 22% 40% 24% 5%	604
	11th to 20th	Day	2 4 32% 38% 20% 4	524
	21st to end	Day	2 4 21% 39% 25% 9%	575
August	1st to 10th	Day	6% 7% 27% 32% 23% 6%	527
	11th to 20th	Day	4 7% 25% 29% 25% 10%	517
	21st to end	Day	6% 8% 23% 28% 25% 10%	583
September	1st to 10th	Day	4 8% 21% 28% 27% 11%	530
	11th to 20th	Day	6% 11% 27% 26% 21% 9%	530
	21st to end	Day	8% 11% 24% 28% 20% 9%	530
October	1st to 10th	Day	14% 11% 21% 24% 19% 12%	429
	11th to 20th	Day	12% 16% 18% 22% 22% 10%	330
	21st to end	Day	13% 15% 22% 33% 15% 3	363
November	1st to 10th	Day	15% 17% 23% 28% 12% 7%	330
	11th to 20th	Day	15% 12% 25% 31% 14% 2	330
	21st to end	Day	12% 15% 25% 30% 15% 2	330
December	1st to 10th	Day	18% 13% 21% 30% 12% 6%	330
	11th to 20th	Day	18% 16% 29% 25% 12%	330
	21st to end	Day	23% 17% 25% 22% 10% 3	280
January	1st to 10th	Night	18% 7% 21% 36% 16% 1	840
	11th to 20th	Night	17% 6% 20% 37% 17% 2	840
	21st to end	Night	16% 6% 23% 38% 16% 2	924
February	1st to 10th	Night	17% 8% 26% 36% 12% 1	840
	11th to 20th	Night	14% 7% 25% 39% 13% 1	804
	21st to end	Night	12% 9% 28% 38% 12% 1	660
March	1st to 10th	Night	13% 8% 24% 42% 12% 2	800
	11th to 20th	Night	12% 6% 23% 42% 17%	800
	21st to end	Night	14% 8% 24% 40% 13% 1	880
April	1st to 10th	Night	13% 9% 23% 38% 15% 1	765
	11th to 20th	Night	13% 9% 29% 37% 11% 1	593
	21st to end	Night	11% 8% 22% 37% 20% 2	600
May	1st to 10th	Night	11% 5% 23% 41% 18% 2	600
	11th to 20th	Night	10% 6% 16% 38% 27% 3	591
	21st to end	Night	12% 5% 17% 37% 24% 4	650
June	1st to 10th	Night	6% 5% 17% 42% 28% 2	554
	11th to 20th	Night	9% 3 22% 46% 21% 1	400
	21st to end	Night	6% 2 10% 49% 29% 5%	400
July	1st to 10th	Night	2 1 11% 48% 35% 4	390
	11th to 20th	Night	2 1 9% 59% 27% 1	473
	21st to end	Night	2 1 8% 48% 37% 3	657
August	1st to 10th	Night	5% 2 9% 51% 31% 2	597
	11th to 20th	Night	2 2 12% 45% 37% 3	594
	21st to end	Night	4 2 13% 47% 30% 5%	660
September	1st to 10th	Night	4 2 13% 42% 35% 4	719
	11th to 20th	Night	7% 3 11% 43% 30% 7%	800
	21st to end	Night	9% 3 13% 39% 30% 6%	800
October	1st to 10th	Night	11% 3 17% 37% 29% 3	800
	11th to 20th	Night	13% 4 16% 36% 28% 3	800
	21st to end	Night	11% 4 19% 43% 21% 3	880
November	1st to 10th	Night	12% 6% 18% 42% 18% 3	820
	11th to 20th	Night	12% 8% 23% 41% 14% 2	891
	21st to end	Night	10% 7% 22% 40% 17% 3	1050
December	1st to 10th	Night	17% 8% 22% 39% 13% 1	1050
	11th to 20th	Night	18% 8% 25% 37% 11% 1	1050
	21st to end	Night	20% 10% 26% 33% 11% 1	1143

Page generated at 2026-02-12 23:42:14. Version ac07

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