Eldorado Star Party
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Eldorado Star Party clear sky chart from 2005-11-06 to 2026-10-29.

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	8% 5% 2 4 3 3 3 3 5% 7% 57%	148854
	Night	7% 5% 1 4 3 3 3 3 5% 7% 60%	143671
Transparency	Day	27% 4 9% 22% 23% 14%	152744
	Night	24% 4 10% 23% 23% 16%	147834
Seeing	Day	9% 6% 24% 33% 23% 6%	17500
	Night	9% 6% 31% 40% 14% 1	27380

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	7% 4 2 4 2 3 3 2 4 7% 63%	5289
	11th to 20th	Day	7% 5% 1 3 2 2 2 3 3 5% 67%	5712
	21st to end	Day	15% 5% 2 5% 3 3 3 3 4 6% 52%	6468
February	1st to 10th	Day	9% 5% 2 5% 3 3 3 3 3 6% 57%	2100
	11th to 20th	Day	9% 6% 2 5% 3 3 4 3 4 5% 56%	2049
	21st to end	Day	9% 4 1 3 3 3 4 3 5% 6% 59%	1730
March	1st to 10th	Day	7% 5% 2 5% 3 3 4 3 4 5% 60%	4600
	11th to 20th	Day	13% 6% 2 4 3 2 3 2 4 5% 57%	5045
	21st to end	Day	6% 5% 2 6% 3 3 3 3 4 6% 56%	5583
April	1st to 10th	Day	8% 4 2 5% 4 3 3 3 5% 7% 58%	2476
	11th to 20th	Day	11% 6% 2 6% 4 3 4 3 4 6% 53%	2494
	21st to end	Day	10% 5% 2 4 3 3 2 3 4 6% 58%	2520
May	1st to 10th	Day	12% 6% 2 6% 3 4 3 3 5% 7% 49%	7454
	11th to 20th	Day	10% 5% 2 5% 4 4 4 3 5% 7% 52%	7627
	21st to end	Day	10% 5% 2 6% 4 4 4 4 6% 8% 47%	8392
June	1st to 10th	Day	4 3 1 3 3 3 4 4 6% 9% 58%	2730
	11th to 20th	Day	6% 4 1 4 3 3 3 4 5% 7% 58%	2730
	21st to end	Day	6% 4 1 4 4 4 4 5% 6% 8% 54%	2730
July	1st to 10th	Day	8% 4 2 4 4 4 4 4 6% 8% 52%	7680
	11th to 20th	Day	9% 5% 2 5% 4 4 5% 4 6% 8% 48%	7680
	21st to end	Day	3 3 1 3 3 3 3 3 4 6% 68%	7966
August	1st to 10th	Day	1 1 1 2 2 2 3 3 4 6% 76%	5545
	11th to 20th	Day	2 1 1 2 2 3 3 3 5% 8% 70%	5483
	21st to end	Day	4 3 1 4 4 3 4 3 5% 9% 61%	6079
September	1st to 10th	Day	10% 5% 2 6% 5% 4 4 4 5% 7% 48%	2399
	11th to 20th	Day	10% 5% 2 5% 5% 4 4 4 6% 7% 47%	2310
	21st to end	Day	8% 4 2 5% 4 4 4 3 6% 7% 54%	2310
October	1st to 10th	Day	6% 3 1 4 4 3 4 2 5% 7% 61%	2310
	11th to 20th	Day	10% 4 2 4 3 2 3 3 4 5% 60%	2310
	21st to end	Day	12% 5% 1 4 2 2 2 2 3 4 63%	2322
November	1st to 10th	Day	10% 5% 1 4 2 3 2 2 4 7% 58%	1853
	11th to 20th	Day	7% 5% 1 4 2 3 3 2 5% 5% 61%	1890
	21st to end	Day	11% 6% 2 5% 2 3 3 2 4 7% 54%	1890
December	1st to 10th	Day	17% 7% 3 6% 3 2 3 2 3 4 50%	3030
	11th to 20th	Day	11% 8% 2 5% 3 3 4 3 5% 4 51%	3481
	21st to end	Day	8% 7% 1 3 2 2 2 2 3 4 68%	4587
January	1st to 10th	Night	6% 5% 2 4 3 3 3 2 4 5% 64%	7634
	11th to 20th	Night	5% 4 2 3 2 1 2 2 3 4 72%	7320
	21st to end	Night	16% 8% 2 4 2 2 3 3 4 5% 50%	7746
February	1st to 10th	Night	8% 6% 2 3 3 2 3 2 4 7% 59%	2520
	11th to 20th	Night	11% 6% 2 5% 3 3 3 2 4 6% 54%	2458
	21st to end	Night	7% 6% 1 3 3 3 3 3 6% 6% 59%	2076
March	1st to 10th	Night	5% 3 1 3 2 3 4 4 6% 8% 61%	5494
	11th to 20th	Night	10% 6% 2 4 2 2 3 2 3 6% 60%	5137
	21st to end	Night	6% 5% 2 4 3 3 3 3 5% 6% 60%	5588
April	1st to 10th	Night	6% 4 2 4 3 3 3 3 6% 7% 58%	2138
	11th to 20th	Night	11% 5% 1 4 3 3 4 3 4 6% 55%	2077
	21st to end	Night	10% 5% 2 3 3 2 2 3 4 4 61%	2100
May	1st to 10th	Night	13% 6% 2 6% 4 3 3 3 4 6% 51%	5427
	11th to 20th	Night	6% 3 1 4 3 3 4 4 5% 8% 58%	5265
	21st to end	Night	8% 5% 2 5% 3 4 5% 4 7% 9% 47%	5793
June	1st to 10th	Night	3 3 1 3 2 3 4 4 7% 10% 61%	1890
	11th to 20th	Night	2 2 1 3 3 3 4 4 6% 10% 62%	1890
	21st to end	Night	5% 3 1 3 4 3 4 3 5% 9% 61%	1890
July	1st to 10th	Night	5% 3 2 5% 3 4 4 3 7% 11% 53%	5308
	11th to 20th	Night	6% 3 1 4 2 3 3 3 6% 8% 60%	5307
	21st to end	Night	2 2 1 3 2 3 3 3 4 7% 71%	6123
August	1st to 10th	Night	2 1 1 2 2 2 2 2 4 6% 76%	4625
	11th to 20th	Night	2 1 1 2 2 2 2 3 5% 9% 71%	4583
	21st to end	Night	3 3 1 3 3 3 4 4 5% 9% 63%	5069
September	1st to 10th	Night	7% 4 3 5% 3 3 4 3 5% 8% 55%	2221
	11th to 20th	Night	8% 4 1 5% 3 4 4 3 7% 8% 53%	2310
	21st to end	Night	6% 4 1 4 3 3 4 4 6% 9% 56%	2310
October	1st to 10th	Night	6% 4 1 4 3 3 3 2 4 6% 65%	2310
	11th to 20th	Night	10% 3 2 4 3 2 3 2 3 4 63%	2310
	21st to end	Night	8% 4 2 4 3 2 2 3 3 4 65%	2668
November	1st to 10th	Night	10% 5% 1 4 2 2 3 2 3 5% 63%	2665
	11th to 20th	Night	7% 5% 1 4 3 3 2 2 4 5% 64%	2730
	21st to end	Night	11% 5% 1 4 3 3 4 3 5% 5% 55%	2730
December	1st to 10th	Night	18% 8% 2 4 2 2 3 2 4 5% 48%	4380
	11th to 20th	Night	9% 7% 2 5% 3 3 3 2 4 5% 56%	4946
	21st to end	Night	7% 7% 2 4 2 2 2 2 4 5% 63%	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	23% 2 5% 24% 28% 18%	5290
	11th to 20th	Day	22% 2 5% 20% 30% 21%	5712
	21st to end	Day	34% 3 5% 16% 26% 16%	6468
February	1st to 10th	Day	30% 3 5% 14% 24% 23%	2100
	11th to 20th	Day	31% 4 6% 21% 22% 17%	2059
	21st to end	Day	27% 4 4 14% 29% 22%	1730
March	1st to 10th	Day	27% 4 4 14% 20% 31%	4600
	11th to 20th	Day	31% 4 4 9% 19% 34%	5045
	21st to end	Day	28% 4 7% 16% 24% 21%	5585
April	1st to 10th	Day	27% 4 7% 19% 22% 21%	2476
	11th to 20th	Day	32% 5% 8% 16% 20% 19%	2494
	21st to end	Day	29% 4 8% 21% 21% 17%	2520
May	1st to 10th	Day	35% 4 9% 14% 21% 17%	7491
	11th to 20th	Day	32% 4 7% 16% 25% 15%	7631
	21st to end	Day	33% 6% 12% 24% 15% 9%	8405
June	1st to 10th	Day	21% 7% 12% 32% 23% 5%	2730
	11th to 20th	Day	24% 5% 12% 23% 27% 9%	2730
	21st to end	Day	25% 7% 14% 25% 22% 6%	2730
July	1st to 10th	Day	29% 6% 14% 33% 17% 1	7616
	11th to 20th	Day	33% 7% 17% 29% 13% 2	7611
	21st to end	Day	17% 5% 14% 31% 30% 4	7792
August	1st to 10th	Day	11% 3 12% 37% 29% 6%	5532
	11th to 20th	Day	14% 4 18% 46% 16% 1	5519
	21st to end	Day	21% 6% 14% 27% 28% 4	6078
September	1st to 10th	Day	35% 5% 11% 21% 19% 8%	2399
	11th to 20th	Day	35% 7% 13% 22% 19% 5%	2310
	21st to end	Day	28% 6% 13% 20% 21% 13%	2310
October	1st to 10th	Day	15% 3 7% 14% 25% 36%	3700
	11th to 20th	Day	28% 3 6% 16% 20% 27%	3678
	21st to end	Day	23% 3 3 20% 38% 13%	3674
November	1st to 10th	Day	27% 4 9% 20% 22% 17%	1853
	11th to 20th	Day	25% 4 9% 18% 22% 22%	1890
	21st to end	Day	32% 3 5% 18% 26% 15%	1890
December	1st to 10th	Day	40% 3 5% 16% 23% 13%	3030
	11th to 20th	Day	36% 4 6% 13% 25% 16%	3479
	21st to end	Day	24% 2 3 18% 29% 24%	4587
January	1st to 10th	Night	23% 3 5% 22% 30% 17%	7635
	11th to 20th	Night	18% 2 4 18% 31% 28%	7320
	21st to end	Night	38% 3 5% 14% 23% 17%	7746
February	1st to 10th	Night	26% 3 7% 15% 26% 23%	2520
	11th to 20th	Night	31% 4 6% 18% 21% 19%	2458
	21st to end	Night	25% 4 6% 13% 27% 24%	2076
March	1st to 10th	Night	20% 4 7% 18% 27% 25%	5494
	11th to 20th	Night	28% 4 4 11% 18% 35%	5137
	21st to end	Night	25% 5% 8% 16% 22% 24%	5588
April	1st to 10th	Night	25% 5% 11% 20% 16% 22%	2138
	11th to 20th	Night	29% 5% 10% 19% 17% 19%	2077
	21st to end	Night	26% 5% 11% 23% 20% 15%	2100
May	1st to 10th	Night	34% 5% 11% 20% 16% 14%	5452
	11th to 20th	Night	24% 5% 10% 21% 26% 14%	5266
	21st to end	Night	31% 7% 17% 23% 14% 8%	5805
June	1st to 10th	Night	17% 7% 17% 33% 22% 4	1890
	11th to 20th	Night	17% 7% 14% 31% 24% 7%	1890
	21st to end	Night	20% 6% 14% 31% 23% 7%	1890
July	1st to 10th	Night	24% 6% 18% 37% 14% 1	5265
	11th to 20th	Night	23% 6% 19% 34% 16% 2	5256
	21st to end	Night	14% 4 14% 35% 29% 3	5987
August	1st to 10th	Night	10% 3 11% 36% 33% 7%	4614
	11th to 20th	Night	11% 4 19% 49% 15% 1	4613
	21st to end	Night	19% 7% 15% 29% 27% 4	5069
September	1st to 10th	Night	27% 7% 12% 25% 20% 9%	2221
	11th to 20th	Night	27% 8% 16% 22% 20% 6%	2310
	21st to end	Night	23% 6% 12% 26% 17% 15%	2310
October	1st to 10th	Night	13% 3 8% 15% 24% 37%	3700
	11th to 20th	Night	24% 3 6% 15% 25% 26%	3680
	21st to end	Night	19% 2 4 25% 33% 16%	4242
November	1st to 10th	Night	25% 3 8% 18% 27% 18%	2665
	11th to 20th	Night	24% 3 7% 21% 24% 21%	2730
	21st to end	Night	30% 4 7% 17% 24% 18%	2730
December	1st to 10th	Night	39% 2 6% 19% 17% 16%	4380
	11th to 20th	Night	32% 3 7% 16% 24% 18%	4947
	21st to end	Night	25% 3 5% 19% 29% 20%	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	12% 9% 42% 28% 8% 2	330
	11th to 20th	Day	14% 10% 34% 28% 13% 2	330
	21st to end	Day	13% 10% 39% 27% 11%	363
February	1st to 10th	Day	17% 10% 32% 24% 14% 2	330
	11th to 20th	Day	13% 10% 45% 26% 5% 1	330
	21st to end	Day	11% 11% 46% 26% 7%	273
March	1st to 10th	Day	14% 12% 41% 27% 6%	330
	11th to 20th	Day	13% 15% 38% 24% 10% 1	330
	21st to end	Day	9% 14% 40% 28% 9%	363
April	1st to 10th	Day	8% 16% 42% 27% 7% 1	496
	11th to 20th	Day	12% 17% 39% 25% 6%	532
	21st to end	Day	9% 14% 43% 28% 6%	540
May	1st to 10th	Day	10% 10% 37% 35% 8%	693
	11th to 20th	Day	13% 9% 35% 31% 11% 1	775
	21st to end	Day	11% 6% 31% 40% 11% 1	844
June	1st to 10th	Day	4 3 21% 46% 23% 2	780
	11th to 20th	Day	6% 2 21% 48% 20% 3	780
	21st to end	Day	5% 2 11% 46% 30% 5%	780
July	1st to 10th	Day	6% 1 8% 39% 38% 8%	771
	11th to 20th	Day	5% 1 5% 40% 42% 7%	768
	21st to end	Day	2 4 35% 43% 15%	722
August	1st to 10th	Day	2 1 4 28% 49% 16%	567
	11th to 20th	Day	7% 3 30% 45% 16%	557
	21st to end	Day	4 1 5% 27% 42% 21%	627
September	1st to 10th	Day	9% 5% 26% 42% 18%	449
	11th to 20th	Day	6% 2 4 29% 45% 14%	360
	21st to end	Day	10% 1 7% 31% 37% 15%	360
October	1st to 10th	Day	3 1 14% 35% 36% 11%	360
	11th to 20th	Day	11% 4 19% 42% 22% 2	360
	21st to end	Day	13% 7% 29% 29% 19% 3	387
November	1st to 10th	Day	12% 9% 28% 31% 18% 2	330
	11th to 20th	Day	14% 8% 23% 30% 20% 5%	330
	21st to end	Day	16% 12% 35% 23% 12% 3	330
December	1st to 10th	Day	15% 8% 29% 32% 13% 3	330
	11th to 20th	Day	13% 10% 34% 28% 12% 3	330
	21st to end	Day	13% 9% 35% 28% 13% 1	363
January	1st to 10th	Night	10% 7% 38% 37% 7%	1050
	11th to 20th	Night	11% 8% 35% 38% 8%	924
	21st to end	Night	13% 9% 38% 33% 7%	924
February	1st to 10th	Night	11% 10% 39% 33% 7%	840
	11th to 20th	Night	15% 11% 41% 29% 4	824
	21st to end	Night	11% 11% 48% 28% 2	692
March	1st to 10th	Night	13% 12% 45% 26% 4	840
	11th to 20th	Night	12% 11% 41% 31% 4	651
	21st to end	Night	8% 10% 51% 28% 2	693
April	1st to 10th	Night	6% 12% 50% 29% 3	630
	11th to 20th	Night	11% 10% 52% 24% 3	623
	21st to end	Night	8% 12% 52% 25% 4	630
May	1st to 10th	Night	6% 9% 52% 29% 4	630
	11th to 20th	Night	8% 8% 43% 33% 7%	621
	21st to end	Night	9% 5% 43% 34% 9% 1	683
June	1st to 10th	Night	3 3 27% 57% 9% 1	630
	11th to 20th	Night	3 1 37% 52% 7%	630
	21st to end	Night	4 2 19% 55% 18% 1	630
July	1st to 10th	Night	6% 10% 57% 26% 2	615
	11th to 20th	Night	3 1 7% 61% 26% 1	612
	21st to end	Night	1 1 5% 62% 31% 1	690
August	1st to 10th	Night	1 5% 55% 37% 2	627
	11th to 20th	Night	5% 7% 50% 35% 3	624
	21st to end	Night	4 1 6% 46% 39% 4	693
September	1st to 10th	Night	6% 1 8% 46% 35% 4	630
	11th to 20th	Night	7% 1 8% 51% 30% 2	630
	21st to end	Night	7% 2 14% 51% 25% 2	630
October	1st to 10th	Night	5% 2 19% 51% 23%	630
	11th to 20th	Night	12% 4 24% 46% 14% 1	630
	21st to end	Night	9% 6% 29% 39% 16% 1	844
November	1st to 10th	Night	12% 4 28% 40% 16%	1025
	11th to 20th	Night	8% 5% 32% 40% 14% 1	1050
	21st to end	Night	14% 7% 33% 34% 12% 1	1050
December	1st to 10th	Night	13% 6% 30% 41% 9% 1	1050
	11th to 20th	Night	13% 8% 34% 37% 8%	1050
	21st to end	Night	10% 6% 38% 36% 9% 1	1155

Page generated at 2026-10-26 03:37:46. Version ac07

Copyright © 2026 Attilla Danko.