El Dorado
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the El Dorado clear sky chart from 2005-11-06 to 2024-12-24.

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% 7% 2 6% 4 4 4 3 5% 7% 44%	101299
	Night	13% 6% 2 5% 4 4 4 3 5% 7% 49%	98755
Transparency	Day	38% 5% 10% 21% 20% 6%	104945
	Night	34% 5% 10% 20% 22% 9%	103250
Seeing	Day	15% 8% 22% 26% 21% 7%	15351
	Night	15% 7% 24% 32% 19% 3	25189

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	19% 12% 3 6% 2 2 2 2 3 4 44%	2847
	11th to 20th	Day	23% 7% 2 4 3 2 3 2 4 5% 46%	2850
	21st to end	Day	23% 8% 3 4 3 2 2 2 3 4 46%	3135
February	1st to 10th	Day	21% 9% 2 6% 4 3 4 3 4 4 40%	1710
	11th to 20th	Day	20% 9% 3 6% 4 3 3 3 5% 4 41%	1814
	21st to end	Day	23% 8% 3 7% 3 4 4 3 4 4 37%	1670
March	1st to 10th	Day	20% 12% 3 8% 4 4 3 3 4 5% 34%	3436
	11th to 20th	Day	16% 7% 3 7% 5% 5% 4 3 5% 7% 38%	3480
	21st to end	Day	15% 8% 3 8% 4 4 4 3 4 6% 42%	3814
April	1st to 10th	Day	13% 7% 2 6% 5% 4 5% 4 6% 6% 43%	2254
	11th to 20th	Day	16% 8% 2 5% 4 4 4 4 5% 6% 41%	2254
	21st to end	Day	11% 6% 2 8% 5% 4 4 4 5% 7% 45%	2280
May	1st to 10th	Day	16% 8% 3 6% 5% 4 5% 4 5% 6% 37%	3765
	11th to 20th	Day	12% 6% 2 7% 4 5% 4 3 6% 7% 43%	3937
	21st to end	Day	12% 7% 2 8% 6% 6% 6% 5% 6% 8% 36%	4477
June	1st to 10th	Day	7% 4 3 6% 6% 5% 6% 5% 8% 8% 41%	2470
	11th to 20th	Day	6% 4 2 6% 6% 5% 6% 5% 6% 9% 45%	2470
	21st to end	Day	5% 4 2 4 5% 6% 5% 5% 9% 10% 45%	2470
July	1st to 10th	Day	8% 6% 2 7% 6% 6% 7% 5% 8% 11% 34%	4120
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 4 7% 10% 42%	4120
	21st to end	Day	15% 9% 3 8% 5% 5% 5% 4 6% 9% 32%	4465
August	1st to 10th	Day	2 2 1 3 3 4 4 3 6% 7% 65%	4056
	11th to 20th	Day	5% 3 2 6% 5% 5% 6% 4 6% 9% 50%	3729
	21st to end	Day	8% 4 2 5% 5% 5% 5% 4 6% 8% 47%	4180
September	1st to 10th	Day	9% 5% 2 5% 5% 5% 5% 5% 5% 7% 46%	2280
	11th to 20th	Day	13% 6% 2 5% 4 4 4 4 6% 8% 42%	2261
	21st to end	Day	9% 4 2 5% 4 4 4 4 5% 6% 54%	1989
October	1st to 10th	Day	7% 4 2 4 4 3 4 2 5% 6% 58%	1900
	11th to 20th	Day	13% 5% 1 3 3 3 2 2 3 6% 58%	1900
	21st to end	Day	17% 5% 2 4 3 3 3 2 4 4 54%	2090
November	1st to 10th	Day	15% 5% 2 5% 4 4 3 3 4 6% 51%	1958
	11th to 20th	Day	11% 5% 2 6% 4 4 3 2 3 5% 53%	2000
	21st to end	Day	17% 7% 3 6% 4 4 3 3 4 5% 45%	2000
December	1st to 10th	Day	17% 9% 3 6% 4 3 3 3 5% 4 43%	1705
	11th to 20th	Day	17% 8% 3 7% 4 4 4 2 4 5% 43%	2251
	21st to end	Day	15% 9% 3 7% 4 4 4 3 4 6% 42%	3162
January	1st to 10th	Night	17% 8% 3 5% 4 3 3 3 3 5% 47%	4108
	11th to 20th	Night	19% 6% 2 5% 3 3 3 2 4 4 50%	4120
	21st to end	Night	24% 8% 2 4 3 2 2 2 3 4 46%	4532
February	1st to 10th	Night	18% 8% 2 6% 3 3 3 3 4 5% 45%	2470
	11th to 20th	Night	20% 7% 3 6% 3 3 3 3 4 5% 43%	2249
	21st to end	Night	22% 8% 2 5% 3 3 2 2 4 5% 44%	1799
March	1st to 10th	Night	19% 8% 2 7% 4 4 3 3 4 6% 40%	3419
	11th to 20th	Night	17% 7% 2 5% 3 4 4 3 6% 8% 42%	3480
	21st to end	Night	14% 7% 2 7% 5% 5% 4 3 5% 7% 42%	3817
April	1st to 10th	Night	12% 4 2 5% 4 4 4 4 6% 6% 49%	1924
	11th to 20th	Night	13% 6% 2 6% 5% 3 4 3 4 6% 48%	1875
	21st to end	Night	10% 6% 2 5% 5% 4 3 3 4 7% 51%	1900
May	1st to 10th	Night	15% 6% 2 6% 4 3 4 4 7% 8% 41%	3130
	11th to 20th	Night	15% 6% 3 6% 3 3 4 3 5% 8% 43%	2960
	21st to end	Night	12% 6% 2 6% 6% 4 5% 4 6% 7% 42%	3090
June	1st to 10th	Night	5% 4 1 4 4 4 4 4 7% 12% 48%	1710
	11th to 20th	Night	5% 3 2 4 4 3 4 4 5% 10% 57%	1710
	21st to end	Night	5% 3 2 4 4 4 4 4 6% 9% 55%	1710
July	1st to 10th	Night	7% 5% 2 5% 4 4 5% 4 7% 11% 44%	2850
	11th to 20th	Night	7% 4 2 6% 4 4 4 4 8% 11% 46%	2850
	21st to end	Night	13% 8% 3 7% 4 4 3 4 7% 8% 39%	3098
August	1st to 10th	Night	2 1 1 2 2 2 3 3 4 9% 72%	2866
	11th to 20th	Night	5% 3 1 4 4 4 5% 5% 7% 11% 52%	3100
	21st to end	Night	4 4 2 5% 4 4 5% 4 7% 9% 51%	3476
September	1st to 10th	Night	7% 4 2 6% 3 5% 5% 3 5% 8% 52%	1900
	11th to 20th	Night	10% 5% 2 6% 3 4 4 4 5% 7% 50%	1914
	21st to end	Night	8% 3 1 4 3 3 4 3 5% 6% 59%	2171
October	1st to 10th	Night	7% 3 1 4 3 3 3 3 4 6% 63%	2280
	11th to 20th	Night	10% 5% 1 4 3 3 3 3 3 5% 60%	2280
	21st to end	Night	13% 5% 1 4 3 3 3 2 4 4 57%	2508
November	1st to 10th	Night	12% 4 2 5% 4 4 3 3 4 5% 53%	2340
	11th to 20th	Night	10% 6% 2 5% 3 3 4 3 4 5% 55%	2400
	21st to end	Night	14% 6% 2 6% 4 3 3 3 3 4 51%	2400
December	1st to 10th	Night	17% 7% 2 5% 3 3 3 3 5% 6% 45%	2575
	11th to 20th	Night	14% 7% 3 6% 4 4 4 3 4 4 47%	3166
	21st to end	Night	16% 8% 3 6% 4 3 3 2 4 5% 46%	4578

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	47% 2 4 18% 26% 4	2848
	11th to 20th	Day	42% 2 11% 20% 21% 4	2850
	21st to end	Day	45% 2 4 16% 25% 8%	3135
February	1st to 10th	Day	48% 3 6% 17% 17% 8%	1710
	11th to 20th	Day	47% 3 6% 18% 19% 7%	1824
	21st to end	Day	51% 4 6% 11% 19% 9%	1670
March	1st to 10th	Day	53% 3 7% 12% 18% 6%	3436
	11th to 20th	Day	45% 5% 8% 20% 18% 4	3480
	21st to end	Day	45% 3 8% 19% 23% 2	3814
April	1st to 10th	Day	41% 5% 8% 21% 18% 8%	2254
	11th to 20th	Day	43% 5% 9% 16% 20% 7%	2254
	21st to end	Day	38% 5% 9% 21% 23% 3	2280
May	1st to 10th	Day	45% 7% 9% 25% 10% 3	3800
	11th to 20th	Day	38% 6% 11% 22% 20% 2	3941
	21st to end	Day	43% 9% 12% 24% 10% 2	4489
June	1st to 10th	Day	37% 9% 13% 24% 16% 1	2470
	11th to 20th	Day	34% 6% 14% 26% 18% 3	2470
	21st to end	Day	31% 7% 15% 25% 19% 3	2470
July	1st to 10th	Day	40% 9% 20% 22% 8%	4056
	11th to 20th	Day	35% 7% 16% 29% 12% 1	4051
	21st to end	Day	48% 7% 13% 23% 9%	4325
August	1st to 10th	Day	18% 5% 15% 29% 28% 5%	4042
	11th to 20th	Day	29% 7% 19% 33% 12% 1	3765
	21st to end	Day	34% 7% 12% 25% 21% 2	4179
September	1st to 10th	Day	36% 7% 13% 18% 18% 8%	2280
	11th to 20th	Day	38% 7% 12% 17% 21% 6%	2261
	21st to end	Day	30% 5% 10% 21% 25% 10%	1989
October	1st to 10th	Day	16% 3 6% 13% 22% 40%	3160
	11th to 20th	Day	18% 2 3 16% 33% 27%	3140
	21st to end	Day	29% 3 4 17% 34% 13%	3428
November	1st to 10th	Day	35% 4 7% 19% 25% 9%	1958
	11th to 20th	Day	35% 3 4 18% 27% 13%	2000
	21st to end	Day	42% 3 6% 17% 25% 7%	2000
December	1st to 10th	Day	44% 4 8% 18% 19% 8%	1705
	11th to 20th	Day	45% 3 5% 17% 23% 6%	2249
	21st to end	Day	43% 3 8% 17% 24% 5%	3162
January	1st to 10th	Night	41% 2 6% 16% 29% 6%	4108
	11th to 20th	Night	40% 3 7% 21% 22% 7%	4120
	21st to end	Night	45% 2 8% 16% 21% 7%	4532
February	1st to 10th	Night	42% 4 7% 17% 22% 8%	2470
	11th to 20th	Night	45% 3 6% 18% 20% 8%	2250
	21st to end	Night	45% 3 7% 14% 19% 12%	1799
March	1st to 10th	Night	46% 4 8% 15% 17% 10%	3419
	11th to 20th	Night	41% 5% 10% 18% 17% 8%	3480
	21st to end	Night	42% 4 8% 18% 25% 3	3817
April	1st to 10th	Night	33% 6% 11% 21% 19% 11%	1924
	11th to 20th	Night	37% 4 9% 16% 22% 11%	1875
	21st to end	Night	33% 5% 8% 25% 24% 5%	1900
May	1st to 10th	Night	39% 7% 11% 24% 15% 4	3160
	11th to 20th	Night	38% 6% 11% 25% 18% 1	2961
	21st to end	Night	38% 9% 13% 23% 14% 2	3099
June	1st to 10th	Night	26% 10% 18% 26% 19% 2	1710
	11th to 20th	Night	23% 6% 15% 30% 23% 4	1710
	21st to end	Night	24% 6% 15% 27% 23% 4	1710
July	1st to 10th	Night	32% 9% 22% 27% 9% 1	2805
	11th to 20th	Night	29% 7% 18% 32% 12% 2	2796
	21st to end	Night	43% 6% 15% 26% 10% 1	2999
August	1st to 10th	Night	11% 4 16% 32% 32% 4	2856
	11th to 20th	Night	24% 6% 19% 31% 17% 3	3130
	21st to end	Night	29% 7% 12% 23% 26% 3	3476
September	1st to 10th	Night	29% 7% 15% 19% 18% 11%	1900
	11th to 20th	Night	33% 6% 11% 18% 24% 8%	1914
	21st to end	Night	26% 5% 9% 22% 26% 13%	2171
October	1st to 10th	Night	16% 3 6% 16% 21% 39%	3800
	11th to 20th	Night	17% 2 4 14% 33% 30%	3779
	21st to end	Night	23% 3 6% 15% 37% 16%	4120
November	1st to 10th	Night	33% 3 8% 17% 26% 12%	2340
	11th to 20th	Night	31% 4 7% 17% 28% 14%	2400
	21st to end	Night	37% 3 6% 18% 26% 9%	2400
December	1st to 10th	Night	41% 4 9% 20% 20% 7%	2575
	11th to 20th	Night	41% 4 6% 14% 25% 10%	3167
	21st to end	Night	41% 3 6% 19% 25% 5%	4578

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	27% 15% 39% 15% 4	270
	11th to 20th	Day	27% 17% 40% 11% 4 1	270
	21st to end	Day	26% 22% 32% 16% 3	297
February	1st to 10th	Day	28% 17% 37% 13% 5%	270
	11th to 20th	Day	36% 20% 33% 8% 2	270
	21st to end	Day	37% 22% 29% 7% 4	225
March	1st to 10th	Day	24% 19% 34% 19% 4	270
	11th to 20th	Day	21% 24% 36% 16% 1	270
	21st to end	Day	24% 18% 40% 15% 3	297
April	1st to 10th	Day	22% 17% 36% 19% 6% 1	434
	11th to 20th	Day	25% 12% 32% 20% 8% 2	452
	21st to end	Day	16% 13% 33% 25% 10% 3	460
May	1st to 10th	Day	17% 9% 33% 28% 11% 2	463
	11th to 20th	Day	15% 4 29% 32% 17% 3	582
	21st to end	Day	10% 4 25% 37% 18% 7%	734
June	1st to 10th	Day	11% 2 13% 35% 29% 10%	680
	11th to 20th	Day	6% 3 15% 36% 31% 8%	680
	21st to end	Day	7% 2 14% 34% 31% 12%	680
July	1st to 10th	Day	10% 2 9% 31% 35% 12%	671
	11th to 20th	Day	8% 2 7% 29% 38% 15%	668
	21st to end	Day	7% 2 6% 31% 37% 16%	739
August	1st to 10th	Day	5% 1 8% 30% 40% 16%	654
	11th to 20th	Day	9% 1 5% 28% 43% 13%	479
	21st to end	Day	13% 1 4 23% 36% 23%	539
September	1st to 10th	Day	10% 2 8% 28% 37% 15%	490
	11th to 20th	Day	14% 2 9% 26% 36% 13%	471
	21st to end	Day	11% 3 14% 37% 26% 8%	300
October	1st to 10th	Day	7% 1 28% 35% 24% 5%	300
	11th to 20th	Day	13% 6% 34% 31% 14% 2	300
	21st to end	Day	24% 7% 31% 22% 13% 2	330
November	1st to 10th	Day	20% 10% 29% 25% 14% 2	300
	11th to 20th	Day	14% 10% 40% 29% 6% 1	300
	21st to end	Day	21% 16% 33% 18% 9% 3	300
December	1st to 10th	Day	24% 12% 41% 18% 3 2	300
	11th to 20th	Day	26% 16% 33% 18% 7%	300
	21st to end	Day	25% 17% 36% 16% 4 2	306
January	1st to 10th	Night	22% 13% 31% 27% 6%	950
	11th to 20th	Night	24% 13% 31% 24% 6% 1	950
	21st to end	Night	23% 13% 33% 28% 4	1045
February	1st to 10th	Night	23% 13% 33% 26% 5%	950
	11th to 20th	Night	24% 13% 37% 22% 3	774
	21st to end	Night	28% 15% 33% 22% 2	543
March	1st to 10th	Night	21% 9% 34% 30% 6%	570
	11th to 20th	Night	22% 9% 34% 29% 5%	570
	21st to end	Night	17% 11% 37% 28% 7%	627
April	1st to 10th	Night	15% 12% 38% 28% 8%	570
	11th to 20th	Night	18% 8% 34% 28% 12% 1	563
	21st to end	Night	14% 9% 36% 31% 10% 1	570
May	1st to 10th	Night	11% 5% 32% 38% 13% 1	570
	11th to 20th	Night	13% 4 28% 36% 17% 2	561
	21st to end	Night	9% 3 22% 37% 26% 4	617
June	1st to 10th	Night	8% 1 11% 42% 34% 4	570
	11th to 20th	Night	5% 1 10% 39% 41% 3	570
	21st to end	Night	5% 1 12% 37% 36% 9%	570
July	1st to 10th	Night	5% 1 8% 35% 40% 10%	555
	11th to 20th	Night	6% 2 4 35% 42% 11%	552
	21st to end	Night	5% 1 6% 38% 37% 12%	624
August	1st to 10th	Night	3 1 6% 34% 44% 13%	567
	11th to 20th	Night	8% 1 4 35% 43% 9%	564
	21st to end	Night	9% 1 6% 29% 43% 11%	627
September	1st to 10th	Night	8% 2 7% 39% 39% 6%	570
	11th to 20th	Night	11% 2 9% 32% 38% 8%	570
	21st to end	Night	9% 2 10% 36% 38% 5%	651
October	1st to 10th	Night	9% 1 13% 39% 33% 5%	760
	11th to 20th	Night	13% 5% 20% 37% 24% 1	760
	21st to end	Night	16% 5% 27% 32% 18% 3	836
November	1st to 10th	Night	15% 4 26% 33% 20% 2	780
	11th to 20th	Night	14% 9% 26% 35% 16% 1	800
	21st to end	Night	17% 8% 30% 33% 12% 1	800
December	1st to 10th	Night	22% 8% 30% 31% 8%	970
	11th to 20th	Night	23% 9% 29% 31% 7%	1000
	21st to end	Night	24% 11% 30% 28% 7%	1063

Page generated at 2024-12-21 03:13:50. Version ac07

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