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 2024-11-01.

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 6% 4 4 5% 4 6% 8% 44%	101285
	Night	12% 6% 2 6% 4 4 4 4 5% 7% 45%	97621
Transparency	Day	39% 4 11% 22% 19% 5%	101097
	Night	38% 3 10% 21% 21% 7%	97480
Seeing	Day	14% 7% 20% 25% 22% 11%	14789
	Night	15% 7% 21% 31% 22% 5%	24272

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 3 3 3 3 5% 5% 43%	2882
	11th to 20th	Day	15% 7% 3 6% 3 3 3 3 4 4 49%	3160
	21st to end	Day	22% 10% 2 4 3 3 2 2 3 5% 44%	3476
February	1st to 10th	Day	18% 10% 2 7% 4 4 4 3 4 6% 39%	1900
	11th to 20th	Day	20% 8% 3 6% 3 4 3 3 4 4 42%	1848
	21st to end	Day	20% 8% 3 8% 5% 3 3 2 3 5% 40%	1570
March	1st to 10th	Day	23% 9% 3 7% 4 4 4 3 5% 6% 32%	3120
	11th to 20th	Day	15% 6% 2 6% 4 4 4 4 6% 7% 42%	3293
	21st to end	Day	15% 7% 3 7% 5% 4 5% 4 6% 7% 39%	4165
April	1st to 10th	Day	12% 5% 2 5% 5% 4 5% 4 5% 6% 47%	2280
	11th to 20th	Day	14% 5% 2 6% 4 4 4 4 5% 6% 45%	2254
	21st to end	Day	9% 5% 1 5% 4 5% 4 3 6% 7% 52%	2280
May	1st to 10th	Day	10% 5% 2 6% 4 4 5% 4 6% 8% 47%	3787
	11th to 20th	Day	14% 5% 2 7% 5% 4 4 4 5% 9% 40%	4081
	21st to end	Day	8% 5% 2 6% 4 5% 5% 5% 7% 9% 43%	4476
June	1st to 10th	Day	9% 5% 2 6% 5% 6% 7% 6% 6% 10% 37%	2470
	11th to 20th	Day	6% 3 2 4 5% 6% 6% 5% 7% 10% 46%	2521
	21st to end	Day	6% 5% 2 6% 6% 5% 5% 5% 7% 10% 42%	2660
July	1st to 10th	Day	7% 5% 2 9% 6% 7% 7% 6% 9% 11% 29%	4440
	11th to 20th	Day	8% 4 2 6% 6% 6% 7% 6% 10% 11% 34%	4099
	21st to end	Day	9% 7% 3 10% 7% 8% 8% 5% 8% 9% 25%	4118
August	1st to 10th	Day	3 2 1 4 4 4 4 4 5% 8% 61%	3785
	11th to 20th	Day	5% 3 1 6% 5% 5% 6% 4 7% 10% 48%	3729
	21st to end	Day	7% 4 2 5% 4 5% 5% 4 7% 10% 47%	4180
September	1st to 10th	Day	10% 5% 3 7% 5% 5% 5% 4 5% 7% 44%	2280
	11th to 20th	Day	14% 6% 2 6% 4 5% 4 4 5% 7% 43%	2118
	21st to end	Day	10% 5% 2 5% 3 4 3 3 6% 6% 52%	2090
October	1st to 10th	Day	8% 4 2 5% 4 4 4 3 5% 5% 57%	2090
	11th to 20th	Day	8% 4 2 5% 3 2 3 3 5% 6% 58%	1991
	21st to end	Day	12% 5% 2 4 3 3 3 3 4 5% 56%	2063
November	1st to 10th	Day	11% 5% 1 4 4 3 3 3 4 4 58%	1672
	11th to 20th	Day	13% 5% 2 5% 4 4 4 3 4 6% 53%	1710
	21st to end	Day	14% 6% 2 5% 4 3 3 4 4 5% 48%	1710
December	1st to 10th	Day	17% 8% 2 5% 4 3 4 3 6% 6% 42%	1710
	11th to 20th	Day	16% 8% 3 6% 4 3 4 3 4 5% 44%	2153
	21st to end	Day	15% 9% 3 7% 3 5% 4 3 5% 7% 40%	3124
January	1st to 10th	Night	18% 11% 2 5% 3 3 3 3 4 5% 42%	4045
	11th to 20th	Night	16% 8% 3 6% 3 3 3 2 3 5% 47%	3800
	21st to end	Night	22% 12% 3 6% 3 3 3 2 2 3 43%	4180
February	1st to 10th	Night	17% 8% 3 6% 4 3 3 3 5% 5% 42%	2280
	11th to 20th	Night	20% 7% 2 5% 3 4 3 3 3 5% 44%	2218
	21st to end	Night	19% 7% 2 6% 5% 4 4 3 4 6% 40%	1884
March	1st to 10th	Night	24% 10% 2 6% 3 3 3 3 4 6% 35%	3733
	11th to 20th	Night	12% 6% 2 6% 4 4 4 4 5% 7% 45%	3695
	21st to end	Night	18% 7% 3 6% 4 4 4 4 5% 4 41%	3466
April	1st to 10th	Night	12% 5% 2 5% 4 4 4 2 6% 7% 48%	1900
	11th to 20th	Night	13% 4 2 5% 3 3 4 3 5% 8% 50%	1875
	21st to end	Night	8% 4 1 5% 3 4 4 4 6% 8% 52%	1900
May	1st to 10th	Night	10% 5% 2 6% 4 4 4 3 5% 8% 47%	3105
	11th to 20th	Night	17% 6% 2 6% 4 4 4 3 5% 7% 42%	2812
	21st to end	Night	7% 4 2 5% 4 5% 5% 5% 8% 10% 46%	3079
June	1st to 10th	Night	7% 5% 2 7% 6% 5% 5% 5% 8% 10% 40%	1710
	11th to 20th	Night	5% 4 1 3 4 3 4 4 8% 13% 50%	1648
	21st to end	Night	4 4 2 4 5% 6% 5% 6% 10% 11% 43%	1520
July	1st to 10th	Night	6% 6% 3 8% 6% 5% 5% 5% 9% 12% 35%	2530
	11th to 20th	Night	7% 4 2 6% 5% 4 6% 6% 10% 13% 38%	2850
	21st to end	Night	8% 8% 4 10% 7% 6% 6% 5% 9% 11% 27%	3435
August	1st to 10th	Night	2 2 1 4 3 3 5% 4 7% 10% 58%	3144
	11th to 20th	Night	4 3 2 5% 4 5% 5% 5% 7% 11% 51%	3100
	21st to end	Night	5% 4 1 6% 5% 5% 5% 5% 7% 9% 47%	3476
September	1st to 10th	Night	9% 5% 2 7% 5% 5% 4 4 7% 9% 43%	1900
	11th to 20th	Night	11% 7% 2 5% 4 4 5% 3 5% 9% 45%	2042
	21st to end	Night	7% 5% 2 6% 4 4 4 4 5% 6% 54%	2090
October	1st to 10th	Night	7% 4 1 4 3 3 3 3 5% 6% 61%	2090
	11th to 20th	Night	12% 5% 2 4 3 2 2 3 5% 7% 57%	2185
	21st to end	Night	14% 5% 2 4 3 2 2 2 3 5% 59%	2532
November	1st to 10th	Night	11% 4 2 4 3 3 4 3 4 5% 57%	2413
	11th to 20th	Night	13% 6% 2 4 3 3 3 2 4 7% 54%	2470
	21st to end	Night	13% 5% 2 5% 3 4 4 4 5% 6% 49%	2470
December	1st to 10th	Night	17% 7% 3 6% 4 3 3 3 4 5% 45%	2470
	11th to 20th	Night	16% 7% 3 6% 4 4 4 2 4 4 47%	3042
	21st to end	Night	18% 8% 3 6% 4 3 4 4 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	54% 1 8% 11% 18% 7%	3120
	11th to 20th	Day	42% 2 7% 21% 20% 8%	3293
	21st to end	Day	46% 2 8% 17% 22% 6%	4165
April	1st to 10th	Day	38% 3 9% 22% 20% 8%	2280
	11th to 20th	Day	40% 2 7% 20% 23% 9%	2254
	21st to end	Day	32% 2 9% 26% 26% 4	2280
May	1st to 10th	Day	37% 2 11% 31% 16% 3	3822
	11th to 20th	Day	42% 2 13% 28% 14% 1	4085
	21st to end	Day	37% 3 14% 30% 16% 1	4489
June	1st to 10th	Day	42% 4 13% 24% 15% 2	2470
	11th to 20th	Day	31% 5% 16% 26% 19% 2	2521
	21st to end	Day	36% 5% 17% 24% 15% 3	2660
July	1st to 10th	Day	43% 10% 21% 20% 6% 1	4371
	11th to 20th	Day	37% 9% 25% 22% 6% 1	4028
	21st to end	Day	53% 8% 13% 19% 7%	3987
August	1st to 10th	Day	21% 4 13% 32% 29% 1	3773
	11th to 20th	Day	30% 7% 16% 30% 15% 2	3765
	21st to end	Day	31% 7% 16% 23% 19% 4	4179
September	1st to 10th	Day	38% 5% 12% 20% 19% 6%	2280
	11th to 20th	Day	41% 5% 11% 16% 22% 5%	2118
	21st to end	Day	32% 4 9% 24% 21% 9%	2090
October	1st to 10th	Day	30% 3 7% 19% 27% 13%	2090
	11th to 20th	Day	28% 3 6% 22% 29% 12%	1991
	21st to end	Day	33% 2 4 18% 32% 11%	2063
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	53% 1 6% 15% 17% 8%	3733
	11th to 20th	Night	39% 2 8% 20% 21% 10%	3695
	21st to end	Night	46% 2 6% 20% 20% 5%	3466
April	1st to 10th	Night	36% 3 10% 21% 20% 10%	1900
	11th to 20th	Night	34% 3 8% 20% 25% 11%	1875
	21st to end	Night	30% 3 9% 25% 26% 6%	1900
May	1st to 10th	Night	38% 2 11% 24% 21% 4	3135
	11th to 20th	Night	43% 2 10% 26% 17% 2	2813
	21st to end	Night	33% 3 13% 27% 20% 4	3087
June	1st to 10th	Night	38% 6% 14% 22% 17% 3	1710
	11th to 20th	Night	26% 4 18% 30% 18% 5%	1648
	21st to end	Night	31% 7% 20% 22% 18% 3	1520
July	1st to 10th	Night	39% 9% 26% 19% 6% 2	2490
	11th to 20th	Night	33% 9% 27% 24% 6% 1	2799
	21st to end	Night	48% 10% 20% 16% 6% 1	3325
August	1st to 10th	Night	18% 6% 16% 35% 23% 2	3132
	11th to 20th	Night	26% 7% 19% 31% 14% 3	3130
	21st to end	Night	31% 7% 16% 20% 21% 5%	3476
September	1st to 10th	Night	37% 5% 15% 19% 18% 6%	1900
	11th to 20th	Night	37% 5% 12% 18% 21% 7%	2042
	21st to end	Night	30% 4 7% 25% 23% 10%	2090
October	1st to 10th	Night	25% 3 8% 21% 25% 17%	2090
	11th to 20th	Night	28% 3 5% 20% 29% 14%	2185
	21st to end	Night	32% 1 5% 17% 30% 15%	2532
November	1st to 10th	Night	31% 2 6% 16% 29% 15%	2413
	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	23% 17% 35% 16% 9%	270
	11th to 20th	Day	19% 20% 35% 21% 4	294
	21st to end	Day	23% 14% 31% 22% 10%	506
April	1st to 10th	Day	18% 14% 30% 25% 11% 2	460
	11th to 20th	Day	19% 13% 27% 25% 13% 3	452
	21st to end	Day	13% 8% 30% 32% 15% 2	460
May	1st to 10th	Day	15% 7% 23% 32% 17% 5%	463
	11th to 20th	Day	10% 3 23% 34% 18% 12%	487
	21st to end	Day	9% 3 20% 31% 24% 14%	529
June	1st to 10th	Day	13% 2 12% 30% 30% 13%	490
	11th to 20th	Day	7% 1 14% 26% 32% 20%	541
	21st to end	Day	8% 4 10% 29% 32% 18%	680
July	1st to 10th	Day	7% 2 7% 29% 37% 18%	671
	11th to 20th	Day	9% 2 4 21% 33% 31%	520
	21st to end	Day	7% 2 7% 21% 36% 27%	532
August	1st to 10th	Day	7% 1 5% 22% 37% 29%	486
	11th to 20th	Day	7% 1 5% 22% 41% 24%	479
	21st to end	Day	15% 1 5% 19% 32% 27%	539
September	1st to 10th	Day	11% 2 7% 29% 35% 17%	490
	11th to 20th	Day	15% 3 8% 24% 36% 14%	490
	21st to end	Day	11% 4 10% 31% 31% 13%	490
October	1st to 10th	Day	11% 2 20% 33% 24% 10%	490
	11th to 20th	Day	9% 4 24% 37% 23% 3	391
	21st to end	Day	17% 10% 23% 32% 15% 3	330
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	20% 12% 30% 29% 9%	760
	11th to 20th	Night	16% 11% 34% 30% 8%	731
	21st to end	Night	18% 9% 33% 28% 12%	627
April	1st to 10th	Night	14% 11% 32% 29% 12%	570
	11th to 20th	Night	15% 8% 33% 30% 13% 1	563
	21st to end	Night	9% 8% 31% 37% 14% 1	570
May	1st to 10th	Night	11% 4 25% 36% 20% 4	570
	11th to 20th	Night	13% 3 17% 36% 26% 4	561
	21st to end	Night	8% 3 12% 36% 33% 7%	617
June	1st to 10th	Night	8% 1 10% 39% 34% 8%	570
	11th to 20th	Night	5% 2 8% 31% 45% 9%	570
	21st to end	Night	5% 2 6% 32% 41% 14%	570
July	1st to 10th	Night	5% 2 4 26% 46% 17%	555
	11th to 20th	Night	5% 1 3 27% 43% 22%	552
	21st to end	Night	6% 2 5% 26% 45% 17%	624
August	1st to 10th	Night	6% 1 4 24% 46% 20%	567
	11th to 20th	Night	7% 1 2 26% 50% 13%	564
	21st to end	Night	12% 1 5% 24% 41% 17%	627
September	1st to 10th	Night	11% 2 7% 29% 41% 10%	570
	11th to 20th	Night	14% 3 10% 29% 38% 7%	712
	21st to end	Night	9% 2 11% 33% 39% 5%	760
October	1st to 10th	Night	9% 1 19% 34% 31% 6%	760
	11th to 20th	Night	14% 5% 19% 38% 21% 3	760
	21st to end	Night	16% 6% 16% 36% 23% 3	836
November	1st to 10th	Night	13% 6% 19% 36% 23% 3	743
	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 2024-10-29 10:20:52. Version ac07

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