Bentonville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bentonville clear sky chart from 2005-11-06 to 2024-12-02.

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% 7% 2 6% 4 4 4 3 5% 7% 45%	101052
	Night	11% 7% 2 5% 3 3 4 3 5% 6% 50%	98666
Transparency	Day	36% 5% 11% 25% 18% 4	104703
	Night	34% 5% 10% 25% 21% 5%	103155
Seeing	Day	16% 10% 27% 26% 16% 5%	15561
	Night	15% 10% 30% 29% 14% 1	25408

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	14% 10% 4 6% 4 3 3 2 4 4 46%	2847
	11th to 20th	Day	9% 7% 4 8% 4 3 3 2 3 5% 51%	2850
	21st to end	Day	21% 10% 3 5% 3 2 2 2 4 5% 43%	3135
February	1st to 10th	Day	17% 11% 4 6% 5% 4 3 3 3 5% 39%	1710
	11th to 20th	Day	15% 11% 3 6% 3 3 3 3 4 7% 43%	1664
	21st to end	Day	17% 9% 3 6% 4 3 4 4 4 5% 41%	1708
March	1st to 10th	Day	16% 7% 2 6% 4 3 3 3 4 5% 47%	3436
	11th to 20th	Day	12% 7% 2 6% 3 4 4 3 4 6% 48%	3480
	21st to end	Day	17% 10% 4 7% 5% 4 4 3 4 5% 36%	3814
April	1st to 10th	Day	13% 8% 2 6% 4 4 4 3 6% 7% 43%	2194
	11th to 20th	Day	16% 8% 3 5% 5% 5% 4 3 5% 6% 40%	2254
	21st to end	Day	18% 10% 3 7% 5% 3 4 3 5% 4 38%	2287
May	1st to 10th	Day	19% 8% 3 7% 5% 5% 5% 4 5% 6% 35%	4082
	11th to 20th	Day	12% 7% 3 7% 5% 5% 4 4 6% 6% 40%	4082
	21st to end	Day	15% 6% 2 6% 5% 5% 5% 4 6% 8% 38%	4477
June	1st to 10th	Day	8% 5% 1 7% 4 4 4 5% 7% 11% 44%	2470
	11th to 20th	Day	7% 4 2 5% 5% 5% 5% 4 6% 8% 47%	2470
	21st to end	Day	4 4 1 4 4 4 4 5% 8% 9% 54%	2470
July	1st to 10th	Day	9% 5% 2 6% 5% 4 6% 5% 7% 10% 41%	4120
	11th to 20th	Day	5% 5% 2 5% 3 5% 5% 4 6% 10% 50%	4120
	21st to end	Day	7% 4 2 5% 5% 4 6% 5% 8% 12% 42%	4465
August	1st to 10th	Day	5% 3 2 4 4 4 4 3 6% 9% 56%	4104
	11th to 20th	Day	9% 5% 2 6% 4 5% 5% 4 6% 8% 46%	3991
	21st to end	Day	4 4 2 5% 4 4 5% 4 6% 8% 55%	4180
September	1st to 10th	Day	10% 6% 2 4 4 4 3 3 4 7% 53%	2280
	11th to 20th	Day	12% 6% 2 6% 4 4 4 4 6% 7% 46%	2123
	21st to end	Day	7% 5% 2 6% 3 4 4 3 5% 8% 54%	2062
October	1st to 10th	Day	9% 4 2 5% 4 3 3 3 6% 7% 55%	1900
	11th to 20th	Day	13% 4 2 4 2 2 3 2 4 6% 58%	1900
	21st to end	Day	18% 6% 2 6% 3 2 3 2 3 4 50%	2090
November	1st to 10th	Day	12% 6% 1 4 3 3 3 3 3 6% 55%	1958
	11th to 20th	Day	12% 7% 2 5% 4 3 3 3 4 5% 51%	1940
	21st to end	Day	17% 8% 3 4 2 2 3 3 3 6% 48%	1685
December	1st to 10th	Day	14% 7% 3 6% 4 3 4 4 4 4 46%	1528
	11th to 20th	Day	14% 11% 3 7% 5% 4 3 2 4 4 42%	2041
	21st to end	Day	17% 15% 7% 6% 4 4 4 4 4 6% 30%	3135
January	1st to 10th	Night	12% 9% 4 8% 4 4 4 3 5% 5% 42%	4108
	11th to 20th	Night	11% 6% 2 7% 3 3 4 3 5% 6% 49%	4120
	21st to end	Night	21% 10% 4 6% 3 2 2 2 3 5% 42%	4532
February	1st to 10th	Night	15% 10% 3 6% 3 4 4 3 6% 6% 42%	2470
	11th to 20th	Night	15% 9% 3 6% 4 3 3 3 3 5% 47%	2403
	21st to end	Night	15% 9% 2 6% 3 4 3 3 5% 4 46%	1760
March	1st to 10th	Night	16% 8% 3 5% 3 3 3 3 4 5% 46%	3419
	11th to 20th	Night	12% 7% 2 6% 3 3 4 3 5% 6% 50%	3480
	21st to end	Night	14% 8% 3 7% 5% 5% 4 3 4 6% 41%	3817
April	1st to 10th	Night	13% 6% 2 4 4 3 3 3 5% 6% 51%	1985
	11th to 20th	Night	13% 6% 3 5% 3 3 4 4 4 7% 48%	1875
	21st to end	Night	17% 7% 2 6% 3 4 3 3 4 6% 44%	1890
May	1st to 10th	Night	13% 8% 3 5% 4 4 4 3 4 7% 44%	2823
	11th to 20th	Night	12% 7% 2 7% 4 4 4 4 5% 7% 42%	2823
	21st to end	Night	13% 6% 2 6% 4 4 4 3 7% 7% 43%	3090
June	1st to 10th	Night	7% 3 1 4 4 3 4 4 6% 9% 55%	1710
	11th to 20th	Night	5% 4 1 4 4 4 3 3 7% 11% 56%	1710
	21st to end	Night	2 2 1 4 3 3 4 4 6% 7% 63%	1710
July	1st to 10th	Night	8% 5% 2 5% 4 4 3 4 6% 8% 52%	2850
	11th to 20th	Night	3 2 1 3 3 3 4 4 5% 8% 64%	2850
	21st to end	Night	6% 3 2 4 4 5% 4 4 7% 10% 51%	3098
August	1st to 10th	Night	2 2 1 3 3 4 5% 4 7% 10% 60%	2836
	11th to 20th	Night	8% 4 2 5% 4 4 4 4 5% 8% 52%	2844
	21st to end	Night	3 3 1 3 3 3 4 4 5% 9% 63%	3476
September	1st to 10th	Night	7% 4 2 4 3 3 4 3 5% 8% 57%	1900
	11th to 20th	Night	8% 5% 2 5% 3 4 4 3 5% 8% 52%	2054
	21st to end	Night	8% 4 2 5% 3 4 3 2 5% 6% 58%	2097
October	1st to 10th	Night	6% 3 1 4 3 3 3 3 5% 8% 61%	2280
	11th to 20th	Night	12% 5% 2 4 3 3 3 3 4 5% 58%	2280
	21st to end	Night	16% 6% 2 5% 3 3 4 2 4 5% 52%	2508
November	1st to 10th	Night	12% 4 2 4 3 3 3 2 4 5% 60%	2340
	11th to 20th	Night	10% 7% 2 4 3 3 3 2 5% 5% 56%	2455
	21st to end	Night	14% 8% 2 4 3 2 3 3 4 5% 52%	2707
December	1st to 10th	Night	13% 8% 4 6% 3 3 3 3 4 6% 47%	2687
	11th to 20th	Night	14% 10% 3 7% 3 4 4 3 3 4 45%	3147
	21st to end	Night	16% 14% 7% 8% 4 4 3 2 4 4 35%	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	43% 2 5% 27% 21% 2	2848
	11th to 20th	Day	37% 4 12% 27% 16% 4	2850
	21st to end	Day	46% 3 7% 21% 18% 5%	3135
February	1st to 10th	Day	49% 3 9% 22% 13% 3	1710
	11th to 20th	Day	44% 3 10% 24% 17% 3	1673
	21st to end	Day	46% 3 6% 20% 16% 8%	1708
March	1st to 10th	Day	40% 3 7% 21% 20% 10%	3436
	11th to 20th	Day	36% 5% 11% 23% 20% 4	3480
	21st to end	Day	50% 5% 9% 24% 11% 1	3814
April	1st to 10th	Day	39% 4 11% 24% 17% 4	2194
	11th to 20th	Day	45% 4 11% 19% 17% 3	2254
	21st to end	Day	49% 4 9% 22% 14% 1	2287
May	1st to 10th	Day	48% 7% 9% 20% 15% 1	4120
	11th to 20th	Day	41% 8% 12% 24% 14%	4086
	21st to end	Day	41% 8% 14% 22% 13% 1	4489
June	1st to 10th	Day	32% 7% 17% 28% 14% 2	2470
	11th to 20th	Day	32% 7% 14% 29% 16% 2	2470
	21st to end	Day	23% 7% 16% 32% 19% 4	2470
July	1st to 10th	Day	35% 7% 17% 25% 14% 2	4056
	11th to 20th	Day	27% 6% 12% 35% 19% 1	4051
	21st to end	Day	31% 8% 21% 30% 10%	4325
August	1st to 10th	Day	24% 5% 15% 30% 21% 5%	4090
	11th to 20th	Day	35% 6% 15% 28% 15% 1	4030
	21st to end	Day	27% 5% 13% 38% 14% 3	4179
September	1st to 10th	Day	32% 4 10% 27% 18% 9%	2280
	11th to 20th	Day	35% 5% 10% 22% 24% 3	2123
	21st to end	Day	29% 4 9% 28% 26% 4	2062
October	1st to 10th	Day	18% 3 6% 17% 39% 18%	3160
	11th to 20th	Day	19% 2 5% 20% 39% 16%	3140
	21st to end	Day	29% 2 8% 31% 24% 5%	3428
November	1st to 10th	Day	32% 3 8% 28% 23% 7%	1958
	11th to 20th	Day	37% 2 6% 23% 21% 10%	1940
	21st to end	Day	40% 3 7% 23% 24% 4	1685
December	1st to 10th	Day	41% 3 8% 27% 19% 2	1528
	11th to 20th	Day	46% 3 5% 19% 24% 3	2039
	21st to end	Day	54% 5% 8% 18% 13% 2	3135
January	1st to 10th	Night	44% 5% 7% 22% 19% 3	4108
	11th to 20th	Night	37% 5% 13% 24% 20% 2	4120
	21st to end	Night	47% 2 10% 18% 19% 3	4532
February	1st to 10th	Night	44% 3 10% 24% 15% 5%	2470
	11th to 20th	Night	41% 3 8% 26% 18% 4	2404
	21st to end	Night	41% 3 8% 20% 21% 7%	1760
March	1st to 10th	Night	41% 4 8% 20% 18% 9%	3419
	11th to 20th	Night	35% 6% 9% 27% 19% 4	3480
	21st to end	Night	44% 6% 9% 26% 14% 1	3817
April	1st to 10th	Night	35% 3 10% 25% 21% 6%	1985
	11th to 20th	Night	36% 4 9% 23% 22% 5%	1875
	21st to end	Night	42% 5% 9% 24% 17% 2	1890
May	1st to 10th	Night	38% 7% 12% 23% 16% 4	2850
	11th to 20th	Night	38% 8% 13% 25% 14% 1	2824
	21st to end	Night	37% 7% 15% 28% 13%	3099
June	1st to 10th	Night	25% 6% 15% 33% 18% 4	1710
	11th to 20th	Night	22% 6% 14% 33% 21% 3	1710
	21st to end	Night	19% 6% 15% 33% 22% 6%	1710
July	1st to 10th	Night	29% 7% 19% 25% 16% 4	2805
	11th to 20th	Night	18% 5% 11% 41% 24% 2	2796
	21st to end	Night	27% 7% 19% 34% 14% 1	2999
August	1st to 10th	Night	18% 7% 15% 35% 24% 1	2826
	11th to 20th	Night	31% 5% 18% 27% 17% 2	2871
	21st to end	Night	19% 5% 12% 39% 22% 4	3476
September	1st to 10th	Night	26% 5% 10% 29% 21% 10%	1900
	11th to 20th	Night	31% 5% 10% 24% 26% 5%	2054
	21st to end	Night	28% 3 8% 25% 31% 5%	2097
October	1st to 10th	Night	13% 3 7% 15% 38% 24%	3800
	11th to 20th	Night	21% 2 4 19% 34% 21%	3779
	21st to end	Night	29% 3 6% 31% 24% 7%	4120
November	1st to 10th	Night	29% 3 8% 25% 26% 9%	2340
	11th to 20th	Night	31% 2 7% 24% 27% 9%	2455
	21st to end	Night	36% 3 7% 22% 26% 5%	2707
December	1st to 10th	Night	39% 3 10% 24% 20% 3	2687
	11th to 20th	Night	45% 3 5% 22% 22% 4	3148
	21st to end	Night	53% 5% 8% 19% 13% 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	25% 17% 37% 17% 4	270
	11th to 20th	Day	24% 24% 38% 13% 1	270
	21st to end	Day	23% 22% 38% 12% 4	297
February	1st to 10th	Day	27% 23% 36% 12% 2	270
	11th to 20th	Day	26% 27% 33% 13% 1	270
	21st to end	Day	33% 23% 35% 7% 2	225
March	1st to 10th	Day	25% 22% 32% 17% 3	270
	11th to 20th	Day	26% 21% 38% 13% 2	270
	21st to end	Day	27% 24% 37% 9% 3 1	297
April	1st to 10th	Day	22% 23% 35% 14% 5% 1	374
	11th to 20th	Day	23% 17% 38% 17% 4 1	452
	21st to end	Day	27% 16% 33% 17% 7%	467
May	1st to 10th	Day	21% 13% 38% 23% 5% 1	653
	11th to 20th	Day	18% 7% 33% 27% 12% 2	675
	21st to end	Day	14% 9% 33% 24% 15% 5%	734
June	1st to 10th	Day	10% 3 20% 36% 25% 6%	680
	11th to 20th	Day	9% 3 22% 38% 22% 8%	680
	21st to end	Day	4 3 29% 36% 23% 5%	680
July	1st to 10th	Day	10% 3 17% 29% 31% 10%	671
	11th to 20th	Day	5% 1 15% 37% 33% 9%	668
	21st to end	Day	7% 1 12% 33% 31% 15%	739
August	1st to 10th	Day	10% 1 12% 42% 28% 7%	676
	11th to 20th	Day	12% 1 12% 36% 32% 7%	641
	21st to end	Day	8% 1 11% 34% 33% 13%	539
September	1st to 10th	Day	12% 2 12% 34% 31% 9%	490
	11th to 20th	Day	9% 17% 45% 22% 7%	333
	21st to end	Day	9% 5% 28% 31% 21% 6%	300
October	1st to 10th	Day	8% 9% 31% 30% 17% 5%	300
	11th to 20th	Day	15% 10% 41% 25% 7% 1	300
	21st to end	Day	26% 14% 36% 19% 5%	330
November	1st to 10th	Day	19% 12% 42% 18% 7% 2	300
	11th to 20th	Day	20% 15% 39% 18% 6% 2	300
	21st to end	Day	25% 19% 32% 19% 5%	300
December	1st to 10th	Day	21% 16% 40% 15% 6% 1	273
	11th to 20th	Day	24% 19% 36% 16% 4 1	270
	21st to end	Day	22% 23% 40% 12% 3	297
January	1st to 10th	Night	20% 19% 35% 23% 4	950
	11th to 20th	Night	21% 20% 36% 19% 4	950
	21st to end	Night	19% 19% 35% 24% 4	1045
February	1st to 10th	Night	22% 17% 37% 22% 3	950
	11th to 20th	Night	20% 18% 41% 18% 2	929
	21st to end	Night	25% 18% 35% 20% 2	504
March	1st to 10th	Night	21% 13% 38% 25% 4	570
	11th to 20th	Night	20% 15% 35% 25% 5%	570
	21st to end	Night	22% 15% 39% 19% 6%	627
April	1st to 10th	Night	17% 17% 38% 23% 5%	570
	11th to 20th	Night	17% 13% 36% 26% 8%	563
	21st to end	Night	22% 10% 38% 21% 9%	570
May	1st to 10th	Night	15% 5% 38% 33% 8%	570
	11th to 20th	Night	16% 5% 29% 33% 16% 1	561
	21st to end	Night	12% 5% 31% 31% 18% 3	617
June	1st to 10th	Night	8% 2 18% 40% 32% 1	570
	11th to 20th	Night	5% 2 28% 41% 22% 2	570
	21st to end	Night	2 1 23% 46% 26% 3	570
July	1st to 10th	Night	6% 1 13% 39% 37% 4	555
	11th to 20th	Night	5% 1 10% 44% 35% 5%	552
	21st to end	Night	6% 1 9% 42% 37% 6%	624
August	1st to 10th	Night	5% 1 11% 44% 35% 4	567
	11th to 20th	Night	8% 1 14% 42% 30% 5%	564
	21st to end	Night	4 1 12% 40% 38% 5%	627
September	1st to 10th	Night	10% 14% 40% 33% 3	570
	11th to 20th	Night	11% 1 14% 41% 29% 4	570
	21st to end	Night	9% 3 22% 37% 25% 4	577
October	1st to 10th	Night	7% 3 27% 36% 22% 4	760
	11th to 20th	Night	15% 8% 34% 32% 11%	760
	21st to end	Night	22% 10% 31% 26% 10% 1	836
November	1st to 10th	Night	14% 9% 38% 27% 11%	780
	11th to 20th	Night	16% 13% 35% 29% 7%	855
	21st to end	Night	21% 14% 35% 22% 9%	1000
December	1st to 10th	Night	19% 13% 37% 25% 6%	960
	11th to 20th	Night	24% 15% 32% 25% 4	950
	21st to end	Night	21% 18% 36% 21% 4	1045

Page generated at 2024-11-29 09:43:07. Version ac07

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