Oleo Acres Double Barrel Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Oleo Acres Double Barrel Observatory clear sky chart from 2005-11-06 to 2025-05-11.

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% 6% 2 5% 4 4 4 3 5% 6% 48%	114518
	Night	12% 6% 2 5% 3 3 3 3 4 6% 53%	114630
Transparency	Day	35% 5% 9% 24% 21% 6%	118211
	Night	32% 4 9% 23% 24% 9%	119066
Seeing	Day	17% 11% 29% 26% 14% 3	15924
	Night	16% 12% 30% 29% 12% 1	25900

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	12% 10% 4 7% 3 3 2 3 3 5% 48%	4077
	11th to 20th	Day	6% 5% 2 5% 3 3 3 3 4 5% 61%	4080
	21st to end	Day	19% 9% 2 4 2 2 2 2 3 5% 49%	4488
February	1st to 10th	Day	20% 9% 2 7% 5% 4 4 3 3 5% 40%	1800
	11th to 20th	Day	16% 9% 3 6% 4 4 3 2 5% 6% 42%	1929
	21st to end	Day	20% 9% 2 6% 3 3 3 3 3 4 45%	1721
March	1st to 10th	Day	18% 7% 2 5% 3 3 3 2 4 4 49%	4936
	11th to 20th	Day	11% 6% 2 6% 3 4 3 3 4 5% 52%	4980
	21st to end	Day	16% 9% 3 6% 4 4 4 3 5% 7% 40%	5462
April	1st to 10th	Day	15% 7% 3 7% 4 3 3 3 4 6% 45%	2200
	11th to 20th	Day	17% 5% 2 6% 4 4 4 3 4 6% 45%	2369
	21st to end	Day	19% 8% 3 6% 4 4 3 3 4 6% 40%	2492
May	1st to 10th	Day	21% 8% 2 7% 4 3 4 3 5% 6% 39%	4212
	11th to 20th	Day	14% 6% 3 6% 4 4 4 4 5% 6% 44%	4083
	21st to end	Day	20% 7% 3 7% 5% 4 4 3 5% 6% 35%	4477
June	1st to 10th	Day	10% 4 2 5% 4 4 6% 4 7% 8% 45%	2470
	11th to 20th	Day	8% 5% 2 6% 4 5% 5% 4 7% 9% 45%	2470
	21st to end	Day	6% 3 2 4 4 4 4 4 7% 8% 54%	2470
July	1st to 10th	Day	8% 5% 2 5% 5% 4 5% 4 7% 9% 47%	4120
	11th to 20th	Day	3 3 1 5% 3 4 5% 4 7% 9% 56%	4120
	21st to end	Day	6% 5% 2 6% 6% 5% 6% 5% 8% 10% 41%	4465
August	1st to 10th	Day	3 3 1 4 4 4 5% 4 6% 7% 60%	4104
	11th to 20th	Day	7% 3 2 5% 3 4 4 4 6% 10% 53%	4041
	21st to end	Day	3 3 1 4 5% 4 5% 5% 7% 9% 54%	4230
September	1st to 10th	Day	11% 6% 1 4 4 3 5% 4 5% 6% 52%	2118
	11th to 20th	Day	10% 4 2 7% 5% 4 5% 3 5% 7% 47%	2090
	21st to end	Day	8% 4 1 4 3 4 5% 4 5% 6% 57%	2090
October	1st to 10th	Day	8% 4 1 4 4 4 4 4 4 5% 58%	1967
	11th to 20th	Day	13% 4 1 4 3 2 2 2 3 4 61%	1900
	21st to end	Day	18% 6% 2 4 3 2 3 2 3 4 53%	2090
November	1st to 10th	Day	13% 6% 2 6% 3 2 3 3 4 7% 52%	1958
	11th to 20th	Day	11% 5% 2 4 3 3 2 2 4 5% 59%	1890
	21st to end	Day	16% 7% 2 5% 3 3 3 2 4 5% 53%	1800
December	1st to 10th	Day	16% 7% 2 4 2 3 3 2 4 5% 52%	2940
	11th to 20th	Day	18% 8% 2 5% 3 3 3 2 4 5% 45%	3391
	21st to end	Day	22% 10% 3 5% 3 3 3 3 4 5% 41%	4488
January	1st to 10th	Night	14% 6% 2 8% 4 3 3 2 4 5% 48%	5888
	11th to 20th	Night	6% 4 2 4 2 3 3 2 4 6% 64%	5900
	21st to end	Night	21% 9% 2 4 2 2 3 2 4 4 47%	6490
February	1st to 10th	Night	15% 9% 3 6% 3 3 4 3 4 5% 46%	2600
	11th to 20th	Night	16% 9% 3 7% 4 4 3 3 4 5% 44%	2373
	21st to end	Night	15% 8% 3 5% 4 3 2 3 3 5% 50%	1906
March	1st to 10th	Night	18% 8% 2 5% 3 3 3 3 4 4 46%	4919
	11th to 20th	Night	11% 5% 2 4 3 3 3 3 4 6% 57%	4980
	21st to end	Night	14% 7% 3 6% 3 3 4 3 5% 6% 45%	5467
April	1st to 10th	Night	14% 6% 2 6% 3 3 3 3 5% 6% 49%	2200
	11th to 20th	Night	13% 6% 2 5% 3 3 4 3 5% 6% 51%	1979
	21st to end	Night	15% 6% 2 5% 3 4 3 3 5% 7% 48%	1903
May	1st to 10th	Night	19% 8% 2 5% 4 3 4 3 6% 6% 39%	2913
	11th to 20th	Night	15% 5% 2 5% 4 4 3 4 5% 8% 46%	2828
	21st to end	Night	15% 5% 2 5% 5% 5% 3 4 6% 8% 42%	3090
June	1st to 10th	Night	6% 3 2 4 3 2 4 3 7% 9% 57%	1710
	11th to 20th	Night	5% 3 2 3 3 3 3 3 7% 9% 59%	1710
	21st to end	Night	4 2 1 2 3 2 3 3 6% 9% 65%	1710
July	1st to 10th	Night	8% 4 2 5% 3 4 4 4 6% 8% 53%	2850
	11th to 20th	Night	3 3 1 3 2 2 3 3 5% 8% 68%	2850
	21st to end	Night	4 4 1 5% 4 4 3 4 7% 9% 54%	3098
August	1st to 10th	Night	2 2 1 3 2 2 4 4 5% 7% 68%	2836
	11th to 20th	Night	4 3 1 3 2 3 4 4 5% 9% 63%	2798
	21st to end	Night	2 2 1 3 3 3 3 3 5% 9% 65%	3414
September	1st to 10th	Night	7% 6% 1 4 3 3 4 3 5% 7% 58%	2057
	11th to 20th	Night	9% 4 1 6% 3 3 4 3 6% 8% 52%	2090
	21st to end	Night	6% 3 1 5% 2 3 3 2 5% 7% 62%	2090
October	1st to 10th	Night	6% 4 1 4 3 2 3 3 4 6% 62%	2192
	11th to 20th	Night	12% 4 2 4 2 2 3 2 4 5% 61%	2280
	21st to end	Night	17% 5% 2 4 2 2 2 2 3 4 56%	2508
November	1st to 10th	Night	13% 5% 2 4 3 2 3 2 4 5% 58%	2340
	11th to 20th	Night	8% 5% 2 4 3 3 3 3 4 5% 59%	2505
	21st to end	Night	16% 6% 2 3 3 3 3 2 4 6% 54%	2600
December	1st to 10th	Night	11% 8% 2 6% 3 3 3 2 3 5% 53%	4250
	11th to 20th	Night	16% 7% 3 6% 3 3 3 2 3 4 51%	4816
	21st to end	Night	18% 11% 3 5% 2 2 2 2 3 5% 47%	6490

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	41% 3 9% 25% 20% 2	4078
	11th to 20th	Day	26% 2 10% 24% 33% 4	4080
	21st to end	Day	41% 3 3 19% 26% 8%	4488
February	1st to 10th	Day	48% 4 8% 16% 21% 5%	1800
	11th to 20th	Day	44% 4 7% 22% 18% 5%	1939
	21st to end	Day	45% 3 4 14% 25% 9%	1721
March	1st to 10th	Day	40% 3 5% 15% 19% 18%	4936
	11th to 20th	Day	35% 3 7% 18% 18% 18%	4980
	21st to end	Day	45% 4 9% 25% 16% 1	5464
April	1st to 10th	Day	42% 3 10% 20% 19% 7%	2200
	11th to 20th	Day	41% 4 9% 21% 19% 6%	2369
	21st to end	Day	46% 5% 8% 21% 18% 3	2492
May	1st to 10th	Day	46% 5% 9% 21% 16% 3	4250
	11th to 20th	Day	39% 7% 11% 24% 19%	4087
	21st to end	Day	49% 6% 11% 17% 13% 4	4489
June	1st to 10th	Day	33% 8% 15% 28% 14% 2	2470
	11th to 20th	Day	33% 7% 13% 26% 18% 2	2470
	21st to end	Day	26% 7% 14% 29% 22% 3	2470
July	1st to 10th	Day	31% 6% 18% 30% 14% 1	4056
	11th to 20th	Day	22% 6% 10% 39% 21% 2	4051
	21st to end	Day	33% 9% 13% 31% 13%	4325
August	1st to 10th	Day	22% 6% 12% 27% 27% 6%	4090
	11th to 20th	Day	27% 5% 18% 34% 15% 1	4080
	21st to end	Day	24% 7% 16% 37% 13% 2	4229
September	1st to 10th	Day	32% 6% 9% 23% 21% 10%	2118
	11th to 20th	Day	35% 6% 9% 21% 20% 8%	2090
	21st to end	Day	27% 5% 8% 22% 28% 9%	2090
October	1st to 10th	Day	18% 3 6% 11% 37% 25%	3266
	11th to 20th	Day	21% 2 4 17% 36% 20%	3140
	21st to end	Day	29% 3 6% 29% 27% 7%	3428
November	1st to 10th	Day	35% 3 7% 23% 25% 7%	1958
	11th to 20th	Day	30% 3 7% 25% 26% 10%	1890
	21st to end	Day	36% 2 7% 21% 27% 7%	1800
December	1st to 10th	Day	36% 3 7% 33% 17% 3	2940
	11th to 20th	Day	42% 3 5% 18% 26% 6%	3389
	21st to end	Day	46% 4 6% 21% 20% 4	4488
January	1st to 10th	Night	39% 3 7% 26% 22% 3	5888
	11th to 20th	Night	23% 3 11% 20% 32% 11%	5900
	21st to end	Night	42% 3 6% 14% 27% 8%	6490
February	1st to 10th	Night	41% 4 9% 20% 20% 7%	2600
	11th to 20th	Night	43% 3 5% 21% 21% 6%	2373
	21st to end	Night	39% 3 7% 17% 23% 12%	1906
March	1st to 10th	Night	42% 3 5% 14% 21% 15%	4919
	11th to 20th	Night	30% 3 6% 22% 16% 23%	4980
	21st to end	Night	39% 4 10% 20% 23% 3	5467
April	1st to 10th	Night	37% 4 9% 19% 19% 12%	2200
	11th to 20th	Night	34% 5% 8% 23% 19% 11%	1979
	21st to end	Night	37% 5% 9% 25% 21% 3	1903
May	1st to 10th	Night	45% 5% 9% 20% 15% 6%	2940
	11th to 20th	Night	36% 7% 13% 26% 16% 2	2829
	21st to end	Night	38% 8% 14% 22% 12% 6%	3099
June	1st to 10th	Night	22% 8% 16% 32% 19% 3	1710
	11th to 20th	Night	23% 5% 12% 33% 24% 4	1710
	21st to end	Night	17% 5% 13% 30% 28% 6%	1710
July	1st to 10th	Night	27% 6% 17% 30% 16% 4	2805
	11th to 20th	Night	16% 4 9% 44% 24% 3	2796
	21st to end	Night	24% 6% 17% 33% 19% 1	2999
August	1st to 10th	Night	14% 5% 11% 29% 33% 8%	2826
	11th to 20th	Night	19% 4 16% 36% 20% 4	2825
	21st to end	Night	18% 4 16% 38% 21% 3	3414
September	1st to 10th	Night	25% 6% 10% 24% 25% 11%	2057
	11th to 20th	Night	30% 6% 9% 22% 24% 10%	2090
	21st to end	Night	22% 3 9% 25% 30% 11%	2090
October	1st to 10th	Night	14% 2 6% 13% 34% 30%	3660
	11th to 20th	Night	18% 2 3 14% 42% 21%	3779
	21st to end	Night	29% 3 4 29% 24% 11%	4120
November	1st to 10th	Night	30% 3 7% 23% 26% 10%	2340
	11th to 20th	Night	29% 3 7% 22% 28% 12%	2505
	21st to end	Night	34% 2 7% 21% 28% 8%	2600
December	1st to 10th	Night	34% 3 7% 27% 23% 5%	4250
	11th to 20th	Night	40% 2 4 18% 25% 11%	4817
	21st to end	Night	43% 3 6% 22% 21% 5%	6490

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	24% 25% 35% 13% 3	300
	11th to 20th	Day	24% 28% 37% 8% 2 1	300
	21st to end	Day	25% 26% 31% 15% 3	330
February	1st to 10th	Day	36% 17% 36% 9% 2	300
	11th to 20th	Day	36% 26% 31% 6% 1	300
	21st to end	Day	37% 24% 29% 7% 2	249
March	1st to 10th	Day	33% 20% 34% 12% 1	300
	11th to 20th	Day	36% 23% 31% 8% 3	300
	21st to end	Day	27% 28% 36% 7% 2	330
April	1st to 10th	Day	31% 21% 36% 10% 2	300
	11th to 20th	Day	30% 20% 35% 12% 3	487
	21st to end	Day	25% 21% 35% 14% 4 1	592
May	1st to 10th	Day	20% 15% 43% 18% 3	703
	11th to 20th	Day	17% 10% 40% 21% 9% 2	676
	21st to end	Day	17% 9% 37% 22% 13% 3	734
June	1st to 10th	Day	11% 4 24% 37% 19% 5%	680
	11th to 20th	Day	9% 4 31% 37% 16% 3	680
	21st to end	Day	5% 3 26% 40% 22% 4	680
July	1st to 10th	Day	8% 2 19% 38% 27% 7%	671
	11th to 20th	Day	4 2 17% 40% 32% 5%	668
	21st to end	Day	5% 2 15% 40% 30% 7%	739
August	1st to 10th	Day	5% 1 13% 47% 28% 4	676
	11th to 20th	Day	10% 2 17% 43% 25% 4	665
	21st to end	Day	5% 1 12% 41% 33% 9%	576
September	1st to 10th	Day	9% 2 10% 39% 32% 8%	328
	11th to 20th	Day	6% 3 24% 40% 24% 4	300
	21st to end	Day	13% 6% 20% 39% 17% 3	300
October	1st to 10th	Day	7% 8% 35% 35% 12% 3	300
	11th to 20th	Day	18% 12% 38% 26% 5%	300
	21st to end	Day	31% 13% 29% 22% 5%	330
November	1st to 10th	Day	16% 17% 40% 20% 5% 2	300
	11th to 20th	Day	20% 20% 35% 20% 3 2	300
	21st to end	Day	27% 21% 35% 14% 3	300
December	1st to 10th	Day	27% 15% 37% 17% 3 1	300
	11th to 20th	Day	31% 19% 37% 10% 4	300
	21st to end	Day	31% 20% 35% 12% 2	330
January	1st to 10th	Night	19% 17% 35% 24% 5%	1000
	11th to 20th	Night	23% 18% 34% 21% 4	1000
	21st to end	Night	20% 18% 33% 25% 4	1100
February	1st to 10th	Night	25% 20% 34% 18% 3	1000
	11th to 20th	Night	26% 22% 33% 16% 3	819
	21st to end	Night	27% 19% 33% 18% 2	586
March	1st to 10th	Night	25% 15% 35% 22% 4	600
	11th to 20th	Night	23% 17% 40% 17% 4	600
	21st to end	Night	19% 20% 36% 20% 4 1	660
April	1st to 10th	Night	20% 18% 36% 21% 5%	600
	11th to 20th	Night	20% 17% 35% 22% 5%	593
	21st to end	Night	18% 17% 37% 21% 8% 1	600
May	1st to 10th	Night	14% 12% 37% 30% 7%	600
	11th to 20th	Night	14% 7% 37% 28% 12% 1	563
	21st to end	Night	11% 7% 34% 31% 17% 1	617
June	1st to 10th	Night	7% 3 25% 40% 22% 3	570
	11th to 20th	Night	7% 2 34% 42% 14% 1	570
	21st to end	Night	3 1 25% 42% 25% 3	570
July	1st to 10th	Night	5% 1 16% 43% 29% 5%	555
	11th to 20th	Night	3 1 17% 49% 27% 3	552
	21st to end	Night	4 1 14% 44% 33% 5%	624
August	1st to 10th	Night	4 1 15% 48% 29% 3	567
	11th to 20th	Night	7% 1 15% 45% 29% 4	564
	21st to end	Night	4 1 14% 44% 33% 4	627
September	1st to 10th	Night	9% 2 14% 43% 29% 3	570
	11th to 20th	Night	11% 2 21% 37% 26% 3	570
	21st to end	Night	7% 2 26% 37% 24% 3	570
October	1st to 10th	Night	9% 6% 31% 32% 21% 3	672
	11th to 20th	Night	15% 10% 32% 31% 12% 1	760
	21st to end	Night	21% 11% 31% 25% 11% 1	836
November	1st to 10th	Night	14% 12% 36% 28% 8% 1	780
	11th to 20th	Night	15% 15% 35% 27% 8%	905
	21st to end	Night	23% 15% 34% 21% 8%	1000
December	1st to 10th	Night	21% 15% 35% 26% 4	1000
	11th to 20th	Night	23% 15% 35% 22% 4	1000
	21st to end	Night	24% 19% 32% 21% 5%	1100

Page generated at 2025-05-08 08:33:54. Version ac07

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