Siloam Springs
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Siloam Springs clear sky chart from 2005-11-06 to 2026-08-15.

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	11% 6% 2 6% 4 4 4 4 5% 7% 47%	143436
	Night	11% 6% 2 5% 3 3 3 3 5% 7% 51%	138689
Transparency	Day	36% 4 11% 26% 19% 4	147048
	Night	34% 3 11% 26% 21% 5%	143157
Seeing	Day	15% 9% 26% 27% 18% 5%	17917
	Night	15% 8% 28% 33% 15% 1	27658

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	13% 10% 4 6% 4 4 3 2 4 5% 46%	5289
	11th to 20th	Day	7% 7% 3 7% 4 3 3 2 3 5% 56%	5310
	21st to end	Day	18% 9% 2 5% 3 2 2 2 4 4 49%	5812
February	1st to 10th	Day	17% 10% 3 7% 5% 3 4 3 4 4 41%	1890
	11th to 20th	Day	16% 9% 3 6% 4 3 4 2 5% 6% 43%	1878
	21st to end	Day	16% 8% 2 5% 4 4 3 4 4 6% 44%	1864
March	1st to 10th	Day	14% 7% 2 5% 3 3 4 3 4 5% 48%	5046
	11th to 20th	Day	9% 6% 2 5% 3 4 4 4 5% 5% 54%	5090
	21st to end	Day	14% 8% 3 7% 5% 5% 5% 4 5% 7% 38%	5583
April	1st to 10th	Day	14% 7% 2 6% 4 4 4 4 5% 7% 44%	2404
	11th to 20th	Day	16% 7% 3 6% 4 5% 4 3 4 5% 42%	2494
	21st to end	Day	18% 9% 3 7% 4 3 5% 4 5% 5% 37%	2552
May	1st to 10th	Day	16% 7% 2 7% 5% 4 4 4 5% 5% 40%	7617
	11th to 20th	Day	13% 6% 2 7% 4 4 5% 4 6% 7% 41%	7627
	21st to end	Day	20% 7% 3 7% 5% 5% 5% 4 6% 7% 31%	8392
June	1st to 10th	Day	8% 5% 2 7% 4 5% 5% 4 8% 9% 44%	2730
	11th to 20th	Day	8% 5% 2 5% 4 4 5% 4 7% 8% 47%	2730
	21st to end	Day	5% 3 1 5% 4 4 4 5% 6% 8% 55%	2730
July	1st to 10th	Day	6% 4 2 5% 4 5% 5% 5% 8% 11% 46%	7680
	11th to 20th	Day	5% 4 2 5% 4 4 5% 4 7% 10% 49%	7680
	21st to end	Day	4 3 2 5% 4 4 5% 4 7% 11% 50%	8337
August	1st to 10th	Day	5% 3 2 4 3 3 3 3 6% 9% 59%	4364
	11th to 20th	Day	9% 4 2 5% 4 5% 4 4 5% 8% 48%	4203
	21st to end	Day	5% 4 2 5% 4 4 5% 4 5% 8% 55%	4312
September	1st to 10th	Day	12% 5% 2 5% 3 3 3 3 5% 7% 53%	2397
	11th to 20th	Day	11% 5% 1 5% 3 5% 5% 4 6% 9% 45%	2200
	21st to end	Day	8% 4 2 5% 4 4 4 3 6% 7% 53%	2190
October	1st to 10th	Day	9% 4 2 5% 3 3 4 3 5% 6% 57%	2000
	11th to 20th	Day	13% 5% 1 4 2 2 2 2 3 6% 59%	2000
	21st to end	Day	18% 6% 2 6% 4 2 3 2 3 4 50%	2200
November	1st to 10th	Day	11% 6% 2 4 3 3 2 3 3 6% 58%	2058
	11th to 20th	Day	11% 7% 2 5% 3 3 3 3 4 5% 53%	2018
	21st to end	Day	16% 8% 3 4 2 3 4 3 4 7% 47%	1890
December	1st to 10th	Day	12% 9% 3 5% 3 3 3 2 4 4 52%	2801
	11th to 20th	Day	12% 9% 2 7% 4 3 3 2 4 5% 49%	3481
	21st to end	Day	19% 16% 6% 6% 3 3 4 3 4 5% 32%	4587
January	1st to 10th	Night	12% 8% 3 7% 5% 3 3 3 4 6% 45%	7634
	11th to 20th	Night	7% 5% 2 5% 3 3 3 3 4 5% 60%	7680
	21st to end	Night	18% 9% 3 6% 3 3 3 3 4 4 43%	8402
February	1st to 10th	Night	15% 10% 2 6% 3 4 3 3 5% 5% 45%	2730
	11th to 20th	Night	15% 9% 2 6% 4 3 3 3 4 6% 46%	2647
	21st to end	Night	14% 8% 2 5% 4 3 4 3 5% 5% 48%	1940
March	1st to 10th	Night	16% 9% 2 6% 3 3 3 3 3 5% 46%	5029
	11th to 20th	Night	10% 6% 2 5% 3 3 3 3 5% 6% 54%	5090
	21st to end	Night	11% 6% 2 6% 4 4 4 4 5% 8% 46%	5588
April	1st to 10th	Night	13% 6% 2 5% 3 4 4 3 4 6% 50%	2215
	11th to 20th	Night	13% 7% 2 5% 3 4 3 4 4 6% 48%	2075
	21st to end	Night	16% 7% 2 6% 3 4 4 3 4 6% 46%	2063
May	1st to 10th	Night	13% 8% 3 6% 3 4 4 3 5% 7% 44%	5266
	11th to 20th	Night	12% 6% 2 6% 4 4 5% 4 6% 8% 44%	5265
	21st to end	Night	18% 8% 3 6% 4 4 4 3 6% 8% 37%	5793
June	1st to 10th	Night	8% 4 1 5% 3 4 3 3 5% 9% 55%	1890
	11th to 20th	Night	5% 4 1 3 4 3 3 4 7% 10% 56%	1890
	21st to end	Night	3 3 1 3 3 3 3 3 6% 8% 63%	1890
July	1st to 10th	Night	6% 3 2 4 4 4 4 4 7% 11% 51%	5308
	11th to 20th	Night	4 3 2 5% 3 3 4 3 6% 9% 58%	5307
	21st to end	Night	3 2 1 4 4 3 4 4 6% 11% 59%	5770
August	1st to 10th	Night	3 2 1 3 3 3 4 4 6% 10% 61%	3016
	11th to 20th	Night	6% 4 2 4 4 5% 4 4 5% 7% 55%	2941
	21st to end	Night	3 3 1 3 3 3 4 3 5% 8% 64%	3586
September	1st to 10th	Night	8% 4 1 4 3 4 4 3 5% 7% 57%	2000
	11th to 20th	Night	9% 4 2 6% 3 3 4 3 5% 6% 54%	2198
	21st to end	Night	8% 5% 1 5% 4 4 3 2 5% 7% 57%	2200
October	1st to 10th	Night	6% 3 1 4 3 3 4 3 4 7% 63%	2390
	11th to 20th	Night	12% 4 1 3 3 3 3 3 4 5% 58%	2400
	21st to end	Night	18% 6% 2 4 3 2 3 2 3 5% 53%	2640
November	1st to 10th	Night	11% 6% 2 3 2 3 3 2 3 5% 61%	2460
	11th to 20th	Night	10% 6% 2 4 2 3 3 3 4 5% 58%	2599
	21st to end	Night	14% 8% 2 4 3 2 2 3 4 5% 52%	2730
December	1st to 10th	Night	10% 10% 2 5% 3 3 3 2 4 5% 53%	4478
	11th to 20th	Night	16% 8% 3 6% 3 3 3 2 3 4 50%	4946
	21st to end	Night	19% 12% 6% 7% 3 3 3 2 3 4 37%	6633

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 6% 27% 19% 2	5290
	11th to 20th	Day	33% 2 8% 28% 24% 5%	5310
	21st to end	Day	41% 2 6% 23% 22% 6%	5812
February	1st to 10th	Day	48% 3 8% 23% 14% 4	1890
	11th to 20th	Day	44% 2 9% 24% 18% 3	1887
	21st to end	Day	43% 2 6% 21% 19% 8%	1864
March	1st to 10th	Day	39% 3 6% 21% 16% 16%	5046
	11th to 20th	Day	32% 3 8% 21% 23% 13%	5090
	21st to end	Day	46% 3 10% 29% 10% 1	5585
April	1st to 10th	Day	40% 4 11% 23% 18% 4	2404
	11th to 20th	Day	44% 3 11% 20% 17% 4	2494
	21st to end	Day	49% 4 9% 22% 14% 1	2552
May	1st to 10th	Day	45% 4 9% 23% 18% 2	7655
	11th to 20th	Day	42% 4 11% 21% 18% 3	7631
	21st to end	Day	51% 5% 12% 17% 15% 1	8405
June	1st to 10th	Day	35% 5% 16% 27% 15% 1	2730
	11th to 20th	Day	33% 5% 15% 29% 16% 2	2730
	21st to end	Day	26% 5% 16% 30% 19% 4	2730
July	1st to 10th	Day	28% 7% 19% 31% 14% 1	7616
	11th to 20th	Day	29% 7% 19% 29% 14% 3	7611
	21st to end	Day	26% 7% 19% 35% 12%	8155
August	1st to 10th	Day	22% 4 16% 30% 23% 4	4350
	11th to 20th	Day	33% 5% 17% 28% 15% 1	4242
	21st to end	Day	27% 5% 13% 39% 13% 3	4311
September	1st to 10th	Day	31% 4 10% 27% 19% 9%	2397
	11th to 20th	Day	34% 5% 11% 24% 22% 4	2200
	21st to end	Day	29% 4 9% 25% 27% 5%	2190
October	1st to 10th	Day	18% 2 6% 17% 39% 18%	3260
	11th to 20th	Day	19% 2 4 20% 40% 15%	3240
	21st to end	Day	29% 2 9% 29% 25% 5%	3538
November	1st to 10th	Day	29% 2 8% 28% 24% 7%	2058
	11th to 20th	Day	35% 2 6% 26% 21% 10%	2018
	21st to end	Day	38% 3 8% 24% 24% 4	1890
December	1st to 10th	Day	38% 2 7% 29% 22% 2	2801
	11th to 20th	Day	40% 2 5% 27% 23% 3	3479
	21st to end	Day	57% 3 6% 21% 12% 2	4587
January	1st to 10th	Night	42% 2 9% 28% 17% 3	7635
	11th to 20th	Night	29% 2 9% 20% 35% 5%	7680
	21st to end	Night	45% 2 8% 18% 24% 4	8402
February	1st to 10th	Night	42% 3 10% 25% 16% 4	2730
	11th to 20th	Night	42% 2 8% 26% 19% 4	2648
	21st to end	Night	39% 2 7% 20% 23% 9%	1940
March	1st to 10th	Night	43% 2 6% 19% 18% 11%	5029
	11th to 20th	Night	32% 2 8% 24% 22% 12%	5090
	21st to end	Night	38% 3 12% 31% 14% 2	5588
April	1st to 10th	Night	36% 2 10% 26% 19% 7%	2215
	11th to 20th	Night	37% 3 9% 24% 21% 6%	2075
	21st to end	Night	41% 4 11% 25% 18% 2	2063
May	1st to 10th	Night	40% 4 11% 24% 17% 3	5293
	11th to 20th	Night	38% 4 14% 24% 16% 4	5266
	21st to end	Night	46% 6% 16% 19% 12% 2	5805
June	1st to 10th	Night	28% 4 16% 31% 18% 3	1890
	11th to 20th	Night	23% 5% 15% 33% 22% 2	1890
	21st to end	Night	19% 5% 17% 31% 23% 5%	1890
July	1st to 10th	Night	26% 6% 18% 31% 16% 3	5265
	11th to 20th	Night	22% 6% 19% 33% 17% 3	5256
	21st to end	Night	20% 6% 18% 39% 17% 1	5641
August	1st to 10th	Night	18% 5% 15% 34% 26% 2	3006
	11th to 20th	Night	28% 6% 18% 28% 18% 2	2968
	21st to end	Night	19% 4 11% 40% 22% 4	3586
September	1st to 10th	Night	27% 4 9% 29% 21% 10%	2000
	11th to 20th	Night	31% 4 10% 26% 25% 5%	2198
	21st to end	Night	28% 2 8% 26% 31% 5%	2200
October	1st to 10th	Night	14% 2 7% 15% 38% 25%	3910
	11th to 20th	Night	20% 2 5% 20% 34% 19%	3899
	21st to end	Night	29% 3 6% 29% 25% 7%	4252
November	1st to 10th	Night	29% 2 8% 25% 28% 8%	2460
	11th to 20th	Night	30% 3 7% 27% 25% 9%	2599
	21st to end	Night	37% 2 8% 23% 25% 6%	2730
December	1st to 10th	Night	35% 2 8% 34% 18% 2	4478
	11th to 20th	Night	41% 2 5% 24% 24% 5%	4947
	21st to end	Night	54% 2 7% 22% 12% 3	6633

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% 14% 40% 16% 6%	330
	11th to 20th	Day	19% 22% 40% 17% 1 1	330
	21st to end	Day	18% 18% 43% 17% 4	363
February	1st to 10th	Day	26% 17% 38% 16% 3	330
	11th to 20th	Day	25% 22% 36% 15% 2	330
	21st to end	Day	27% 21% 36% 13% 3	273
March	1st to 10th	Day	26% 18% 35% 18% 3	330
	11th to 20th	Day	26% 20% 33% 17% 4	330
	21st to end	Day	27% 15% 41% 12% 4 1	363
April	1st to 10th	Day	21% 20% 32% 20% 6% 1	424
	11th to 20th	Day	24% 16% 36% 18% 6% 1	532
	21st to end	Day	24% 15% 34% 19% 8% 1	572
May	1st to 10th	Day	18% 11% 37% 27% 7%	753
	11th to 20th	Day	17% 9% 31% 28% 12% 3	775
	21st to end	Day	13% 6% 32% 27% 15% 6%	844
June	1st to 10th	Day	11% 4 21% 33% 25% 7%	780
	11th to 20th	Day	9% 4 18% 37% 25% 7%	780
	21st to end	Day	4 3 22% 39% 27% 5%	780
July	1st to 10th	Day	8% 2 13% 31% 32% 13%	771
	11th to 20th	Day	6% 1 12% 35% 35% 10%	768
	21st to end	Day	7% 2 8% 33% 35% 15%	849
August	1st to 10th	Day	8% 2 11% 40% 31% 8%	776
	11th to 20th	Day	10% 1 9% 33% 37% 10%	728
	21st to end	Day	8% 2 9% 31% 39% 11%	583
September	1st to 10th	Day	10% 2 9% 34% 34% 10%	527
	11th to 20th	Day	7% 15% 42% 25% 11%	330
	21st to end	Day	10% 5% 21% 30% 23% 10%	330
October	1st to 10th	Day	9% 5% 28% 30% 21% 6%	330
	11th to 20th	Day	14% 11% 33% 30% 11% 2	330
	21st to end	Day	25% 15% 29% 23% 6% 1	363
November	1st to 10th	Day	13% 11% 43% 25% 7% 2	330
	11th to 20th	Day	17% 15% 38% 21% 8% 1	330
	21st to end	Day	23% 15% 34% 21% 7%	330
December	1st to 10th	Day	21% 12% 44% 16% 6% 2	330
	11th to 20th	Day	22% 14% 42% 16% 5% 1	330
	21st to end	Day	25% 18% 39% 14% 4	363
January	1st to 10th	Night	18% 14% 33% 30% 5%	1050
	11th to 20th	Night	18% 15% 39% 23% 5%	1050
	21st to end	Night	16% 12% 39% 29% 4	1155
February	1st to 10th	Night	20% 13% 38% 25% 4	1050
	11th to 20th	Night	20% 16% 39% 22% 3	1013
	21st to end	Night	21% 14% 38% 24% 3	556
March	1st to 10th	Night	20% 11% 37% 27% 5%	630
	11th to 20th	Night	21% 11% 34% 30% 4	630
	21st to end	Night	17% 12% 40% 25% 5%	693
April	1st to 10th	Night	17% 11% 39% 28% 5%	630
	11th to 20th	Night	17% 11% 36% 28% 8%	623
	21st to end	Night	21% 6% 41% 23% 8% 1	630
May	1st to 10th	Night	16% 6% 30% 39% 9%	630
	11th to 20th	Night	15% 5% 25% 37% 17% 1	621
	21st to end	Night	13% 4 27% 34% 20% 2	683
June	1st to 10th	Night	9% 4 14% 41% 30% 1	630
	11th to 20th	Night	6% 2 21% 46% 24% 1	630
	21st to end	Night	3 2 18% 45% 30% 2	630
July	1st to 10th	Night	7% 2 8% 40% 38% 5%	615
	11th to 20th	Night	5% 1 9% 40% 40% 5%	612
	21st to end	Night	4 2 6% 38% 44% 5%	690
August	1st to 10th	Night	4 1 8% 47% 36% 3	627
	11th to 20th	Night	8% 1 7% 46% 33% 5%	606
	21st to end	Night	5% 1 8% 39% 42% 5%	660
September	1st to 10th	Night	11% 1 10% 41% 35% 2	600
	11th to 20th	Night	11% 1 11% 42% 31% 4	600
	21st to end	Night	11% 3 18% 39% 27% 3	600
October	1st to 10th	Night	7% 2 22% 39% 26% 4	790
	11th to 20th	Night	14% 6% 30% 38% 12%	800
	21st to end	Night	22% 7% 28% 32% 9% 1	880
November	1st to 10th	Night	14% 7% 37% 31% 11%	820
	11th to 20th	Night	14% 10% 35% 32% 8%	919
	21st to end	Night	20% 10% 34% 28% 8%	1050
December	1st to 10th	Night	18% 12% 34% 30% 5%	1050
	11th to 20th	Night	22% 11% 35% 28% 5%	1050
	21st to end	Night	21% 13% 35% 28% 4	1155

Page generated at 2026-08-12 02:37:16. Version ac07

Copyright © 2026 Attilla Danko.