Barnes Bend Acess Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Barnes Bend Acess Area clear sky chart from 2005-11-06 to 2024-03-06.

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	12% 6% 2 5% 5% 3 5% 5% 5% 7% 44%	79527
	Night	13% 6% 2 5% 5% 3 4 4 5% 7% 47%	79967
Transparency	Day	40% 3 10% 21% 20% 5%	79256
	Night	38% 3 10% 20% 22% 7%	79759
Seeing	Day	15% 7% 20% 25% 22% 11%	13834
	Night	15% 7% 21% 31% 22% 5%	23490

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% 11% 2 4 4 2 3 4 5% 5% 43%	2882
	11th to 20th	Day	15% 6% 3 5% 4 2 3 4 4 4 49%	3160
	21st to end	Day	22% 10% 2 3 3 2 2 3 3 5% 44%	3476
February	1st to 10th	Day	18% 9% 3 6% 4 3 4 4 4 6% 40%	1900
	11th to 20th	Day	20% 7% 3 5% 4 3 4 3 3 5% 42%	1848
	21st to end	Day	20% 7% 3 7% 6% 3 3 3 3 6% 40%	1570
March	1st to 10th	Day	16% 7% 3 6% 4 3 4 4 3 6% 44%	1850
	11th to 20th	Day	15% 7% 3 6% 6% 3 4 5% 4 6% 40%	1863
	21st to end	Day	13% 6% 2 5% 5% 3 4 5% 6% 8% 43%	2376
April	1st to 10th	Day	12% 5% 2 4 5% 3 4 5% 5% 7% 48%	2160
	11th to 20th	Day	13% 4 3 5% 5% 3 4 5% 5% 7% 46%	2134
	21st to end	Day	9% 5% 1 5% 4 3 4 4 5% 8% 52%	2160
May	1st to 10th	Day	12% 5% 2 4 4 2 4 4 4 7% 50%	2168
	11th to 20th	Day	9% 5% 3 6% 6% 3 5% 6% 6% 9% 44%	2301
	21st to end	Day	8% 4 3 5% 5% 3 6% 6% 6% 9% 44%	2531
June	1st to 10th	Day	9% 5% 2 6% 5% 5% 8% 7% 6% 10% 37%	2340
	11th to 20th	Day	6% 3 2 3 5% 4 6% 7% 7% 10% 47%	2388
	21st to end	Day	7% 4 2 5% 6% 4 6% 6% 8% 10% 42%	2520
July	1st to 10th	Day	9% 5% 3 8% 7% 5% 7% 7% 8% 10% 32%	2520
	11th to 20th	Day	8% 5% 2 5% 7% 5% 8% 7% 8% 11% 35%	2333
	21st to end	Day	6% 4 3 7% 7% 5% 8% 8% 8% 11% 34%	2350
August	1st to 10th	Day	5% 4 2 5% 7% 4 7% 7% 7% 10% 41%	2148
	11th to 20th	Day	8% 5% 2 5% 8% 5% 8% 6% 7% 11% 35%	2125
	21st to end	Day	12% 6% 3 6% 6% 4 5% 6% 7% 9% 37%	2376
September	1st to 10th	Day	10% 4 3 6% 6% 3 5% 5% 6% 7% 44%	2160
	11th to 20th	Day	13% 5% 3 5% 5% 4 5% 4 5% 7% 44%	2007
	21st to end	Day	10% 4 2 4 4 3 3 5% 5% 6% 54%	1980
October	1st to 10th	Day	8% 4 2 5% 4 3 4 3 4 5% 56%	1980
	11th to 20th	Day	9% 4 2 4 4 2 3 4 5% 7% 56%	1887
	21st to end	Day	12% 5% 2 3 3 3 3 4 4 5% 55%	1955
November	1st to 10th	Day	11% 4 1 4 4 3 3 3 4 5% 58%	1672
	11th to 20th	Day	13% 4 2 4 4 3 4 4 4 6% 53%	1710
	21st to end	Day	14% 6% 2 4 5% 2 4 4 4 5% 49%	1710
December	1st to 10th	Day	17% 7% 3 4 5% 3 3 4 5% 7% 42%	1710
	11th to 20th	Day	16% 8% 4 5% 5% 2 4 4 4 5% 44%	2153
	21st to end	Day	15% 9% 3 6% 4 3 5% 4 5% 6% 41%	3124
January	1st to 10th	Night	18% 11% 3 4 4 3 3 3 4 5% 43%	4045
	11th to 20th	Night	16% 8% 4 5% 4 2 3 3 3 5% 47%	3800
	21st to end	Night	22% 11% 3 5% 4 2 3 2 2 3 43%	4180
February	1st to 10th	Night	17% 7% 3 5% 5% 2 3 4 5% 5% 42%	2280
	11th to 20th	Night	20% 7% 3 5% 4 3 3 3 3 5% 44%	2218
	21st to end	Night	19% 6% 3 5% 6% 3 4 4 4 6% 40%	1884
March	1st to 10th	Night	16% 6% 2 5% 4 3 4 4 4 7% 47%	2227
	11th to 20th	Night	16% 5% 2 5% 5% 3 4 5% 4 7% 42%	2111
	21st to end	Night	13% 6% 3 5% 4 3 4 6% 7% 5% 46%	1980
April	1st to 10th	Night	12% 5% 2 5% 4 3 4 4 5% 8% 49%	1800
	11th to 20th	Night	13% 4 2 5% 3 2 4 4 5% 8% 51%	1775
	21st to end	Night	8% 3 2 4 4 3 5% 4 6% 8% 53%	1800
May	1st to 10th	Night	10% 3 2 3 4 2 3 4 4 8% 56%	1789
	11th to 20th	Night	10% 6% 2 5% 5% 3 5% 5% 6% 9% 44%	1592
	21st to end	Night	7% 3 2 4 4 4 5% 5% 7% 10% 49%	1744
June	1st to 10th	Night	7% 4 2 6% 6% 3 6% 6% 7% 10% 42%	1620
	11th to 20th	Night	5% 3 2 3 4 3 4 5% 7% 13% 51%	1562
	21st to end	Night	5% 3 2 4 5% 4 6% 6% 10% 11% 44%	1440
July	1st to 10th	Night	6% 4 2 6% 7% 5% 6% 5% 8% 10% 41%	1440
	11th to 20th	Night	5% 3 2 4 5% 3 5% 6% 9% 11% 46%	1614
	21st to end	Night	5% 3 3 5% 6% 3 6% 6% 9% 13% 41%	1968
August	1st to 10th	Night	4 3 2 4 5% 3 6% 7% 10% 14% 42%	1790
	11th to 20th	Night	6% 4 2 5% 6% 4 7% 6% 7% 11% 41%	1776
	21st to end	Night	9% 5% 3 6% 7% 4 5% 6% 6% 8% 41%	1980
September	1st to 10th	Night	9% 4 2 6% 6% 4 4 5% 7% 9% 44%	1800
	11th to 20th	Night	10% 6% 3 4 4 2 5% 5% 6% 9% 46%	1934
	21st to end	Night	7% 4 2 5% 5% 3 4 5% 5% 6% 54%	1980
October	1st to 10th	Night	7% 4 1 4 4 2 3 4 4 7% 60%	1980
	11th to 20th	Night	13% 4 2 3 3 1 2 3 5% 7% 55%	2070
	21st to end	Night	14% 5% 3 4 3 2 2 2 3 5% 57%	2398
November	1st to 10th	Night	10% 4 2 4 4 3 4 3 4 5% 57%	2406
	11th to 20th	Night	13% 5% 2 3 4 2 3 3 4 6% 54%	2470
	21st to end	Night	14% 5% 2 4 4 3 4 4 5% 6% 49%	2470
December	1st to 10th	Night	17% 7% 3 6% 4 2 4 3 4 5% 45%	2470
	11th to 20th	Night	16% 7% 3 5% 5% 3 4 3 4 4 47%	3042
	21st to end	Night	18% 8% 3 5% 5% 2 4 5% 5% 7% 38%	4532

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	46% 1 4 22% 23% 4	2883
	11th to 20th	Day	41% 1 6% 25% 22% 4	3160
	21st to end	Day	46% 1 6% 19% 20% 8%	3476
February	1st to 10th	Day	48% 2 5% 21% 17% 7%	1900
	11th to 20th	Day	48% 2 4 18% 21% 8%	1858
	21st to end	Day	49% 2 6% 15% 20% 8%	1570
March	1st to 10th	Day	43% 2 7% 16% 20% 11%	1850
	11th to 20th	Day	45% 3 10% 16% 19% 6%	1863
	21st to end	Day	40% 3 9% 23% 22% 3	2376
April	1st to 10th	Day	37% 3 9% 23% 21% 7%	2160
	11th to 20th	Day	39% 2 7% 21% 24% 8%	2134
	21st to end	Day	32% 2 8% 26% 27% 4	2160
May	1st to 10th	Day	36% 2 9% 25% 23% 5%	2168
	11th to 20th	Day	37% 4 15% 25% 18% 1	2305
	21st to end	Day	36% 5% 12% 26% 20% 2	2531
June	1st to 10th	Day	42% 4 12% 25% 15% 2	2340
	11th to 20th	Day	30% 6% 17% 27% 18% 2	2388
	21st to end	Day	36% 5% 17% 24% 14% 3	2520
July	1st to 10th	Day	44% 7% 19% 19% 9% 2	2451
	11th to 20th	Day	40% 8% 23% 19% 9% 1	2262
	21st to end	Day	40% 8% 20% 23% 9%	2219
August	1st to 10th	Day	36% 6% 21% 27% 10% 1	2136
	11th to 20th	Day	41% 8% 18% 20% 10% 3	2125
	21st to end	Day	43% 6% 16% 21% 10% 5%	2376
September	1st to 10th	Day	38% 5% 12% 21% 19% 5%	2160
	11th to 20th	Day	40% 5% 12% 16% 22% 5%	2007
	21st to end	Day	32% 4 9% 24% 22% 10%	1980
October	1st to 10th	Day	31% 3 7% 20% 27% 11%	1980
	11th to 20th	Day	29% 3 6% 23% 29% 10%	1887
	21st to end	Day	34% 2 4 18% 32% 10%	1955
November	1st to 10th	Day	31% 1 6% 22% 29% 11%	1672
	11th to 20th	Day	34% 3 6% 18% 28% 11%	1710
	21st to end	Day	40% 2 7% 18% 25% 8%	1710
December	1st to 10th	Day	43% 3 10% 19% 20% 6%	1710
	11th to 20th	Day	46% 1 7% 17% 25% 4	2150
	21st to end	Day	47% 1 5% 21% 23% 2	3124
January	1st to 10th	Night	47% 1 4 15% 28% 4	4045
	11th to 20th	Night	43% 1 3 22% 21% 9%	3800
	21st to end	Night	50% 1 1 17% 25% 5%	4180
February	1st to 10th	Night	45% 2 6% 18% 21% 8%	2280
	11th to 20th	Night	45% 3 4 16% 20% 11%	2219
	21st to end	Night	47% 2 7% 16% 18% 11%	1884
March	1st to 10th	Night	40% 2 6% 17% 23% 13%	2227
	11th to 20th	Night	42% 3 9% 18% 20% 7%	2111
	21st to end	Night	38% 3 8% 23% 21% 6%	1980
April	1st to 10th	Night	36% 3 10% 22% 20% 10%	1800
	11th to 20th	Night	33% 3 8% 21% 25% 10%	1775
	21st to end	Night	29% 3 9% 25% 27% 6%	1800
May	1st to 10th	Night	29% 3 9% 26% 26% 7%	1789
	11th to 20th	Night	38% 3 14% 23% 18% 3	1593
	21st to end	Night	30% 6% 12% 25% 23% 4	1745
June	1st to 10th	Night	37% 6% 14% 23% 17% 2	1620
	11th to 20th	Night	25% 4 19% 31% 18% 5%	1562
	21st to end	Night	30% 7% 20% 22% 17% 3	1440
July	1st to 10th	Night	35% 7% 23% 23% 9% 3	1400
	11th to 20th	Night	28% 10% 26% 23% 10% 1	1563
	21st to end	Night	31% 7% 27% 23% 9% 2	1858
August	1st to 10th	Night	28% 7% 24% 29% 11% 1	1778
	11th to 20th	Night	35% 9% 21% 19% 11% 5%	1776
	21st to end	Night	40% 7% 17% 19% 13% 5%	1980
September	1st to 10th	Night	37% 5% 15% 20% 19% 5%	1800
	11th to 20th	Night	36% 5% 13% 18% 21% 8%	1934
	21st to end	Night	30% 4 7% 24% 24% 11%	1980
October	1st to 10th	Night	26% 3 9% 22% 26% 16%	1980
	11th to 20th	Night	30% 3 6% 20% 29% 12%	2070
	21st to end	Night	34% 1 5% 16% 29% 15%	2398
November	1st to 10th	Night	31% 2 6% 16% 29% 15%	2406
	11th to 20th	Night	33% 2 5% 20% 27% 13%	2470
	21st to end	Night	36% 2 6% 22% 22% 11%	2470
December	1st to 10th	Night	43% 2 10% 18% 22% 5%	2470
	11th to 20th	Night	42% 2 6% 16% 29% 6%	3044
	21st to end	Night	47% 2 5% 17% 26% 3	4532

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% 19% 32% 21% 4	270
	11th to 20th	Day	23% 19% 34% 14% 8% 1	270
	21st to end	Day	23% 21% 37% 16% 3 1	297
February	1st to 10th	Day	21% 19% 39% 14% 6% 1	270
	11th to 20th	Day	33% 14% 32% 17% 4	270
	21st to end	Day	26% 24% 35% 13% 2	225
March	1st to 10th	Day	24% 17% 34% 16% 9%	255
	11th to 20th	Day	19% 23% 35% 19% 5%	262
	21st to end	Day	23% 15% 29% 23% 11%	462
April	1st to 10th	Day	16% 13% 30% 27% 12% 2	420
	11th to 20th	Day	17% 14% 26% 25% 14% 3	412
	21st to end	Day	14% 9% 29% 31% 14% 2	420
May	1st to 10th	Day	16% 8% 21% 33% 17% 5%	423
	11th to 20th	Day	10% 3 21% 34% 20% 13%	447
	21st to end	Day	9% 2 18% 30% 26% 15%	485
June	1st to 10th	Day	13% 2 10% 30% 30% 14%	450
	11th to 20th	Day	7% 1 12% 26% 33% 21%	498
	21st to end	Day	8% 4 10% 29% 32% 18%	630
July	1st to 10th	Day	8% 2 6% 27% 38% 19%	621
	11th to 20th	Day	9% 1 4 21% 32% 32%	478
	21st to end	Day	6% 1 6% 20% 37% 29%	488
August	1st to 10th	Day	7% 1 4 20% 37% 31%	446
	11th to 20th	Day	7% 1 4 21% 41% 26%	439
	21st to end	Day	16% 1 5% 18% 32% 27%	495
September	1st to 10th	Day	10% 2 6% 27% 37% 18%	450
	11th to 20th	Day	14% 2 8% 23% 38% 15%	450
	21st to end	Day	10% 2 9% 32% 33% 13%	450
October	1st to 10th	Day	12% 1 19% 32% 25% 11%	450
	11th to 20th	Day	10% 4 24% 36% 23% 3	357
	21st to end	Day	19% 11% 24% 32% 12% 2	297
November	1st to 10th	Day	17% 6% 28% 30% 13% 6%	270
	11th to 20th	Day	15% 11% 37% 26% 11% 1	270
	21st to end	Day	13% 15% 31% 25% 13% 3	270
December	1st to 10th	Day	26% 11% 34% 19% 9% 1	270
	11th to 20th	Day	24% 11% 34% 20% 9% 1	270
	21st to end	Day	27% 11% 34% 20% 5% 1	297
January	1st to 10th	Night	22% 13% 34% 25% 6%	760
	11th to 20th	Night	23% 14% 27% 28% 8%	760
	21st to end	Night	22% 13% 33% 29% 4	836
February	1st to 10th	Night	21% 12% 30% 31% 5%	760
	11th to 20th	Night	25% 13% 31% 26% 5%	743
	21st to end	Night	22% 15% 34% 26% 2	628
March	1st to 10th	Night	19% 12% 31% 29% 9%	743
	11th to 20th	Night	16% 11% 33% 30% 9%	693
	21st to end	Night	17% 9% 33% 28% 12%	594
April	1st to 10th	Night	13% 11% 31% 31% 13%	540
	11th to 20th	Night	15% 8% 32% 30% 14% 2	533
	21st to end	Night	9% 8% 31% 36% 14% 1	540
May	1st to 10th	Night	12% 4 25% 37% 20% 3	540
	11th to 20th	Night	12% 3 17% 36% 27% 4	531
	21st to end	Night	8% 3 10% 36% 35% 8%	584
June	1st to 10th	Night	8% 1 10% 38% 35% 8%	540
	11th to 20th	Night	5% 2 8% 29% 45% 10%	540
	21st to end	Night	5% 2 6% 32% 41% 14%	540
July	1st to 10th	Night	5% 2 3 26% 46% 17%	525
	11th to 20th	Night	4 1 3 27% 42% 22%	522
	21st to end	Night	5% 2 5% 26% 45% 18%	591
August	1st to 10th	Night	6% 1 4 22% 47% 20%	537
	11th to 20th	Night	8% 1 2 25% 51% 13%	534
	21st to end	Night	12% 1 5% 23% 42% 17%	594
September	1st to 10th	Night	10% 2 6% 29% 43% 10%	540
	11th to 20th	Night	13% 2 10% 30% 38% 7%	674
	21st to end	Night	9% 1 11% 34% 40% 5%	720
October	1st to 10th	Night	9% 1 20% 33% 32% 6%	720
	11th to 20th	Night	14% 5% 19% 37% 22% 3	720
	21st to end	Night	17% 6% 17% 35% 22% 3	792
November	1st to 10th	Night	12% 6% 19% 36% 24% 3	740
	11th to 20th	Night	15% 7% 28% 34% 16% 1	760
	21st to end	Night	17% 7% 26% 36% 12% 2	760
December	1st to 10th	Night	22% 10% 25% 33% 10%	760
	11th to 20th	Night	23% 8% 28% 31% 10%	760
	21st to end	Night	25% 10% 29% 30% 6%	836

Page generated at 2024-03-03 05:28:59. Version ac07

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