Sulphur Springs
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sulphur Springs clear sky chart from 2005-11-06 to 2026-05-17.

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% 4 4 4 3 5% 7% 49%	132338
	Night	12% 5% 2 5% 3 3 3 3 4 6% 53%	130792
Transparency	Day	35% 4 9% 25% 21% 7%	135990
	Night	32% 3 9% 22% 24% 10%	135204
Seeing	Day	14% 6% 22% 28% 23% 8%	17174
	Night	14% 6% 26% 34% 18% 2	27102

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% 6% 2 6% 3 3 3 3 4 6% 50%	5289
	11th to 20th	Day	8% 5% 2 3 2 3 3 3 5% 7% 61%	5310
	21st to end	Day	23% 9% 3 6% 4 3 3 2 3 4 41%	5812
February	1st to 10th	Day	19% 8% 3 7% 4 4 3 2 3 5% 42%	1895
	11th to 20th	Day	20% 8% 3 6% 4 3 3 2 4 6% 42%	2049
	21st to end	Day	20% 8% 2 4 2 2 2 2 3 5% 50%	1844
March	1st to 10th	Day	17% 8% 2 5% 3 3 3 2 5% 6% 46%	5046
	11th to 20th	Day	14% 5% 2 4 3 3 3 3 4 6% 54%	5090
	21st to end	Day	13% 8% 3 6% 4 4 4 4 5% 6% 44%	5583
April	1st to 10th	Day	14% 7% 3 6% 5% 3 3 3 4 7% 44%	2310
	11th to 20th	Day	15% 6% 2 5% 4 4 4 4 6% 5% 44%	2483
	21st to end	Day	14% 6% 2 6% 4 5% 4 4 5% 7% 42%	2538
May	1st to 10th	Day	17% 8% 3 7% 4 4 4 3 5% 6% 39%	5992
	11th to 20th	Day	14% 6% 3 8% 5% 4 4 4 5% 5% 43%	5941
	21st to end	Day	14% 8% 3 8% 5% 5% 5% 4 6% 7% 37%	6434
June	1st to 10th	Day	7% 4 2 5% 4 5% 6% 4 8% 9% 46%	2600
	11th to 20th	Day	6% 4 2 6% 5% 5% 5% 5% 6% 10% 48%	2600
	21st to end	Day	4 3 1 4 4 4 5% 5% 7% 10% 54%	2600
July	1st to 10th	Day	8% 5% 2 7% 6% 6% 6% 5% 7% 10% 39%	5900
	11th to 20th	Day	3 2 1 3 3 3 3 4 6% 10% 62%	5900
	21st to end	Day	6% 5% 2 6% 4 4 5% 5% 6% 8% 48%	6422
August	1st to 10th	Day	2 1 1 3 3 3 4 3 5% 8% 68%	4234
	11th to 20th	Day	5% 2 1 4 3 4 4 5% 6% 9% 57%	4153
	21st to end	Day	4 4 2 6% 4 4 6% 5% 8% 10% 47%	4312
September	1st to 10th	Day	9% 6% 2 5% 4 4 5% 4 5% 7% 50%	2220
	11th to 20th	Day	10% 5% 2 7% 4 4 4 3 7% 8% 47%	2200
	21st to end	Day	8% 4 1 4 3 3 4 3 6% 8% 58%	2200
October	1st to 10th	Day	6% 3 2 4 3 3 4 3 4 7% 61%	2069
	11th to 20th	Day	13% 4 1 4 3 3 3 2 3 4 60%	2000
	21st to end	Day	15% 6% 1 5% 2 3 2 2 4 5% 56%	2200
November	1st to 10th	Day	11% 5% 2 5% 4 3 3 3 4 6% 54%	2058
	11th to 20th	Day	9% 5% 2 4 3 3 3 3 4 5% 58%	2066
	21st to end	Day	16% 6% 2 5% 3 3 3 3 3 5% 52%	1890
December	1st to 10th	Day	19% 4 2 4 3 2 3 2 4 5% 52%	3030
	11th to 20th	Day	18% 9% 2 6% 4 4 3 2 4 5% 43%	3481
	21st to end	Day	18% 9% 3 5% 3 3 3 3 4 4 45%	4587
January	1st to 10th	Night	13% 6% 2 4 3 3 3 3 4 5% 54%	7634
	11th to 20th	Night	7% 3 1 3 2 2 2 2 3 5% 70%	7680
	21st to end	Night	25% 7% 2 6% 3 3 3 2 3 4 40%	8402
February	1st to 10th	Night	15% 7% 2 5% 3 3 3 2 4 5% 50%	2730
	11th to 20th	Night	17% 7% 3 6% 3 2 3 2 3 5% 48%	2468
	21st to end	Night	17% 6% 2 4 3 3 3 2 3 4 52%	1961
March	1st to 10th	Night	18% 7% 2 6% 4 3 3 2 4 6% 45%	5029
	11th to 20th	Night	10% 5% 2 5% 4 4 4 3 4 7% 53%	5090
	21st to end	Night	13% 6% 2 5% 4 3 4 3 5% 6% 49%	5588
April	1st to 10th	Night	12% 5% 2 4 4 3 4 4 5% 7% 51%	2310
	11th to 20th	Night	12% 6% 2 5% 3 3 4 4 5% 6% 49%	2085
	21st to end	Night	11% 6% 1 4 4 4 3 3 5% 8% 51%	2077
May	1st to 10th	Night	16% 8% 3 7% 4 4 4 3 6% 7% 38%	4143
	11th to 20th	Night	11% 6% 2 6% 4 4 5% 4 5% 7% 45%	4107
	21st to end	Night	11% 6% 2 6% 4 4 4 3 6% 9% 45%	4443
June	1st to 10th	Night	5% 4 2 5% 4 3 3 3 6% 11% 55%	1800
	11th to 20th	Night	4 4 1 3 3 2 2 3 6% 7% 64%	1800
	21st to end	Night	4 3 1 4 3 3 4 4 6% 9% 59%	1800
July	1st to 10th	Night	6% 4 2 6% 4 5% 4 4 8% 12% 43%	4078
	11th to 20th	Night	4 2 1 2 2 2 3 2 5% 11% 66%	4077
	21st to end	Night	3 3 1 5% 4 4 4 4 7% 9% 55%	4449
August	1st to 10th	Night	2 1 2 1 2 2 2 5% 8% 74%	2926
	11th to 20th	Night	4 2 1 2 2 3 3 3 6% 10% 64%	2904
	21st to end	Night	3 3 1 4 4 4 4 4 7% 10% 56%	3586
September	1st to 10th	Night	7% 4 1 5% 3 4 3 3 5% 7% 57%	2175
	11th to 20th	Night	10% 4 1 5% 3 3 3 3 5% 7% 54%	2200
	21st to end	Night	6% 3 2 4 3 3 4 2 5% 6% 63%	2200
October	1st to 10th	Night	6% 3 1 3 3 3 2 3 5% 6% 67%	2310
	11th to 20th	Night	12% 3 1 3 2 2 3 2 3 5% 65%	2400
	21st to end	Night	15% 5% 2 3 2 2 2 1 3 4 61%	2640
November	1st to 10th	Night	10% 5% 2 4 3 3 3 3 3 5% 60%	2460
	11th to 20th	Night	8% 5% 2 5% 3 3 3 3 4 6% 59%	2551
	21st to end	Night	14% 6% 2 5% 4 3 3 2 3 5% 53%	2730
December	1st to 10th	Night	16% 7% 2 5% 3 2 2 2 3 4 53%	4380
	11th to 20th	Night	16% 7% 3 6% 4 4 3 2 2 4 49%	4946
	21st to end	Night	15% 8% 3 5% 3 3 3 2 3 5% 50%	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	37% 2 7% 28% 24% 2	5290
	11th to 20th	Day	25% 1 6% 27% 34% 6%	5310
	21st to end	Day	50% 1 3 16% 21% 9%	5812
February	1st to 10th	Day	47% 3 5% 18% 20% 8%	1895
	11th to 20th	Day	46% 2 7% 21% 17% 7%	2059
	21st to end	Day	40% 2 5% 16% 27% 10%	1844
March	1st to 10th	Day	40% 3 5% 16% 20% 15%	5046
	11th to 20th	Day	33% 4 6% 18% 19% 20%	5090
	21st to end	Day	42% 3 9% 23% 19% 4	5585
April	1st to 10th	Day	41% 4 9% 21% 17% 9%	2310
	11th to 20th	Day	40% 5% 8% 19% 21% 7%	2483
	21st to end	Day	41% 5% 8% 22% 20% 4	2538
May	1st to 10th	Day	47% 4 10% 25% 12% 2	6030
	11th to 20th	Day	43% 4 9% 20% 21% 2	5945
	21st to end	Day	45% 5% 10% 21% 15% 3	6447
June	1st to 10th	Day	31% 8% 14% 29% 16% 2	2600
	11th to 20th	Day	30% 6% 15% 26% 19% 4	2600
	21st to end	Day	24% 5% 15% 32% 21% 3	2600
July	1st to 10th	Day	40% 4 20% 28% 7%	5836
	11th to 20th	Day	20% 3 15% 40% 21% 1	5831
	21st to end	Day	32% 4 14% 35% 14% 1	6240
August	1st to 10th	Day	15% 4 12% 32% 29% 7%	4220
	11th to 20th	Day	23% 4 16% 41% 14% 2	4192
	21st to end	Day	30% 5% 18% 32% 13% 2	4311
September	1st to 10th	Day	33% 5% 8% 22% 21% 10%	2220
	11th to 20th	Day	34% 5% 12% 22% 20% 7%	2200
	21st to end	Day	25% 4 9% 22% 28% 12%	2200
October	1st to 10th	Day	14% 3 7% 13% 31% 33%	3368
	11th to 20th	Day	20% 2 3 21% 33% 22%	3240
	21st to end	Day	26% 2 4 31% 28% 9%	3538
November	1st to 10th	Day	33% 4 6% 22% 26% 9%	2058
	11th to 20th	Day	29% 3 8% 21% 28% 11%	2066
	21st to end	Day	37% 2 6% 21% 27% 8%	1890
December	1st to 10th	Day	38% 2 4 29% 23% 4	3030
	11th to 20th	Day	45% 2 4 16% 26% 7%	3479
	21st to end	Day	44% 2 5% 21% 23% 5%	4587
January	1st to 10th	Night	35% 2 7% 24% 28% 4	7635
	11th to 20th	Night	21% 1 6% 19% 37% 16%	7680
	21st to end	Night	50% 1 4 14% 20% 10%	8402
February	1st to 10th	Night	38% 3 7% 21% 21% 11%	2730
	11th to 20th	Night	42% 2 6% 18% 23% 8%	2468
	21st to end	Night	38% 3 6% 16% 23% 15%	1961
March	1st to 10th	Night	43% 3 5% 13% 20% 16%	5029
	11th to 20th	Night	33% 3 6% 17% 18% 23%	5090
	21st to end	Night	37% 3 8% 20% 27% 5%	5588
April	1st to 10th	Night	33% 4 10% 23% 18% 12%	2310
	11th to 20th	Night	35% 4 10% 20% 21% 11%	2085
	21st to end	Night	33% 4 11% 23% 24% 5%	2077
May	1st to 10th	Night	46% 5% 12% 22% 13% 4	4170
	11th to 20th	Night	38% 4 15% 19% 21% 3	4108
	21st to end	Night	35% 6% 15% 24% 12% 9%	4452
June	1st to 10th	Night	24% 6% 15% 30% 21% 3	1800
	11th to 20th	Night	19% 5% 13% 35% 22% 6%	1800
	21st to end	Night	20% 6% 14% 30% 26% 4	1800
July	1st to 10th	Night	33% 4 21% 30% 12%	4035
	11th to 20th	Night	15% 4 16% 41% 22% 3	4026
	21st to end	Night	25% 5% 17% 35% 17% 3	4320
August	1st to 10th	Night	10% 3 12% 30% 38% 7%	2916
	11th to 20th	Night	17% 4 14% 43% 18% 5%	2931
	21st to end	Night	22% 5% 19% 31% 21% 2	3586
September	1st to 10th	Night	27% 5% 9% 23% 25% 10%	2175
	11th to 20th	Night	29% 4 9% 26% 22% 10%	2200
	21st to end	Night	23% 3 8% 22% 30% 15%	2200
October	1st to 10th	Night	12% 2 5% 15% 27% 39%	3778
	11th to 20th	Night	17% 2 4 16% 36% 26%	3899
	21st to end	Night	25% 2 3 27% 27% 16%	4252
November	1st to 10th	Night	28% 3 7% 20% 27% 14%	2460
	11th to 20th	Night	28% 2 7% 21% 26% 15%	2551
	21st to end	Night	36% 2 7% 18% 27% 9%	2730
December	1st to 10th	Night	38% 2 6% 21% 26% 7%	4380
	11th to 20th	Night	42% 2 5% 14% 24% 12%	4947
	21st to end	Night	39% 2 5% 20% 26% 8%	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	21% 12% 37% 24% 5% 1	330
	11th to 20th	Day	16% 17% 42% 18% 6% 1	330
	21st to end	Day	22% 13% 38% 20% 7%	363
February	1st to 10th	Day	25% 10% 43% 17% 5%	330
	11th to 20th	Day	27% 18% 38% 15% 3	330
	21st to end	Day	29% 15% 39% 13% 3 1	273
March	1st to 10th	Day	24% 11% 38% 21% 6%	330
	11th to 20th	Day	25% 17% 38% 15% 4 1	330
	21st to end	Day	17% 13% 39% 25% 5%	363
April	1st to 10th	Day	21% 14% 36% 21% 8% 1	330
	11th to 20th	Day	23% 10% 37% 19% 10%	521
	21st to end	Day	21% 10% 32% 27% 9% 2	558
May	1st to 10th	Day	16% 9% 32% 32% 10% 1	753
	11th to 20th	Day	15% 6% 26% 35% 14% 3	756
	21st to end	Day	16% 3 22% 36% 19% 4	789
June	1st to 10th	Day	8% 2 15% 33% 30% 12%	730
	11th to 20th	Day	8% 1 15% 39% 31% 6%	730
	21st to end	Day	4 2 11% 33% 38% 13%	730
July	1st to 10th	Day	7% 2 7% 33% 38% 13%	721
	11th to 20th	Day	2 1 6% 34% 44% 14%	718
	21st to end	Day	6% 2 3 30% 44% 16%	794
August	1st to 10th	Day	3 1 4 28% 49% 14%	726
	11th to 20th	Day	10% 1 2 30% 42% 14%	710
	21st to end	Day	9% 1 4 24% 39% 24%	583
September	1st to 10th	Day	9% 2 6% 24% 37% 23%	350
	11th to 20th	Day	6% 1 8% 24% 36% 25%	330
	21st to end	Day	12% 2 9% 28% 31% 18%	330
October	1st to 10th	Day	4 17% 36% 35% 9%	330
	11th to 20th	Day	11% 4 29% 31% 19% 6%	330
	21st to end	Day	23% 8% 23% 25% 18% 3	363
November	1st to 10th	Day	19% 4 29% 28% 16% 4	330
	11th to 20th	Day	15% 6% 33% 33% 11% 2	330
	21st to end	Day	19% 10% 36% 22% 11% 2	330
December	1st to 10th	Day	21% 12% 33% 25% 8% 2	330
	11th to 20th	Day	22% 10% 38% 22% 7% 2	330
	21st to end	Day	24% 13% 34% 23% 4 1	363
January	1st to 10th	Night	18% 9% 36% 30% 7%	1050
	11th to 20th	Night	18% 14% 34% 28% 6% 1	1050
	21st to end	Night	20% 9% 36% 30% 5%	1155
February	1st to 10th	Night	20% 9% 38% 27% 6%	1050
	11th to 20th	Night	23% 12% 37% 25% 3	834
	21st to end	Night	24% 15% 34% 24% 3	577
March	1st to 10th	Night	20% 11% 33% 29% 6%	630
	11th to 20th	Night	16% 11% 37% 30% 6%	630
	21st to end	Night	16% 10% 36% 33% 5%	693
April	1st to 10th	Night	14% 10% 41% 28% 7%	630
	11th to 20th	Night	16% 11% 38% 26% 9%	623
	21st to end	Night	12% 7% 40% 32% 8% 1	630
May	1st to 10th	Night	13% 5% 37% 37% 8% 1	630
	11th to 20th	Night	11% 5% 31% 35% 16% 2	609
	21st to end	Night	9% 4 25% 40% 20% 2	650
June	1st to 10th	Night	7% 1 15% 41% 33% 3	600
	11th to 20th	Night	5% 1 17% 50% 27% 2	600
	21st to end	Night	5% 10% 39% 39% 7%	600
July	1st to 10th	Night	4 1 7% 41% 41% 6%	585
	11th to 20th	Night	4 1 5% 39% 46% 5%	582
	21st to end	Night	2 1 5% 42% 42% 8%	657
August	1st to 10th	Night	3 1 2 41% 47% 5%	597
	11th to 20th	Night	8% 1 3 35% 47% 7%	594
	21st to end	Night	5% 3 37% 45% 9%	660
September	1st to 10th	Night	9% 1 6% 35% 43% 7%	600
	11th to 20th	Night	12% 1 6% 33% 43% 5%	600
	21st to end	Night	7% 1 11% 41% 36% 4	600
October	1st to 10th	Night	8% 1 15% 42% 30% 3	710
	11th to 20th	Night	12% 4 23% 40% 19% 2	800
	21st to end	Night	17% 6% 29% 31% 16% 1	880
November	1st to 10th	Night	13% 4 27% 39% 15% 1	820
	11th to 20th	Night	10% 8% 32% 38% 11% 1	871
	21st to end	Night	17% 9% 34% 30% 10% 1	1050
December	1st to 10th	Night	17% 8% 32% 35% 7%	1050
	11th to 20th	Night	21% 8% 32% 32% 6%	1050
	21st to end	Night	19% 9% 34% 32% 6%	1155

Page generated at 2026-05-14 00:58:53. Version ac07

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