Hot Springs
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hot Springs clear sky chart from 2005-11-06 to 2026-01-17.

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	8% 6% 2 5% 3 4 4 4 6% 7% 53%	136244
	Night	7% 6% 2 6% 4 4 4 4 5% 7% 51%	132867
Transparency	Day	30% 5% 13% 28% 19% 5%	131031
	Night	32% 5% 13% 27% 18% 4	129087
Seeing	Day	12% 12% 31% 29% 14% 2	17486
	Night	10% 9% 34% 37% 10% 1	27559

By Month

Percentage Cloud Cover SW (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	2 8% 4 7% 5% 6% 5% 4 6% 7% 46%	3718
	11th to 20th	Day	3 9% 4 10% 5% 5% 5% 4 6% 7% 43%	3688
	21st to end	Day	2 6% 3 7% 4 3 3 3 4 6% 59%	4046
February	1st to 10th	Day	7% 10% 5% 8% 6% 5% 4 4 5% 6% 41%	1800
	11th to 20th	Day	6% 9% 3 9% 5% 4 4 4 5% 7% 44%	1923
	21st to end	Day	4 9% 3 6% 4 4 4 4 6% 6% 49%	1650
March	1st to 10th	Day	6% 9% 2 6% 3 4 3 2 4 6% 55%	4500
	11th to 20th	Day	8% 7% 2 4 3 3 3 3 5% 6% 58%	4666
	21st to end	Day	16% 10% 3 5% 3 4 4 3 5% 7% 40%	5969
April	1st to 10th	Day	11% 11% 3 5% 3 3 3 3 5% 8% 46%	2400
	11th to 20th	Day	12% 10% 3 6% 4 4 5% 4 5% 6% 41%	2371
	21st to end	Day	15% 7% 3 6% 5% 4 3 3 5% 8% 42%	2527
May	1st to 10th	Day	11% 5% 2 6% 4 4 4 4 6% 7% 47%	5985
	11th to 20th	Day	15% 6% 2 5% 3 4 4 4 6% 7% 43%	6298
	21st to end	Day	18% 5% 2 4 3 3 4 4 5% 7% 45%	6925
June	1st to 10th	Day	8% 4 2 4 3 3 4 4 7% 9% 52%	2800
	11th to 20th	Day	9% 4 1 4 3 3 4 4 6% 8% 52%	2800
	21st to end	Day	5% 3 1 3 2 3 3 4 6% 8% 62%	2800
July	1st to 10th	Day	4 3 1 4 3 4 4 4 6% 10% 56%	6339
	11th to 20th	Day	7% 2 1 3 3 4 4 4 7% 9% 56%	6340
	21st to end	Day	7% 3 1 4 2 3 5% 4 7% 9% 56%	6903
August	1st to 10th	Day	6% 4 1 4 3 3 5% 4 6% 9% 54%	6232
	11th to 20th	Day	4 3 1 3 3 3 4 3 7% 8% 60%	5489
	21st to end	Day	5% 4 2 5% 4 4 4 4 7% 8% 52%	5984
September	1st to 10th	Day	6% 3 1 3 3 3 3 3 4 7% 63%	2400
	11th to 20th	Day	8% 4 1 3 3 2 3 3 5% 7% 62%	2315
	21st to end	Day	9% 4 1 3 3 2 2 2 3 5% 64%	2200
October	1st to 10th	Day	7% 4 1 3 2 2 1 2 3 4 72%	3430
	11th to 20th	Day	9% 5% 2 3 2 3 2 2 4 6% 63%	3204
	21st to end	Day	8% 6% 2 5% 4 4 4 4 5% 7% 52%	3190
November	1st to 10th	Day	6% 7% 2 4 3 3 5% 4 6% 9% 53%	1853
	11th to 20th	Day	3 7% 2 4 3 4 4 3 6% 7% 57%	1890
	21st to end	Day	5% 7% 2 6% 4 3 4 3 5% 7% 53%	1711
December	1st to 10th	Day	2 6% 2 5% 3 4 3 3 4 6% 60%	2700
	11th to 20th	Day	2 3 2 6% 3 4 4 3 6% 8% 59%	3106
	21st to end	Day	6% 9% 3 6% 4 4 4 4 5% 5% 49%	4092
January	1st to 10th	Night	3 11% 4 11% 6% 4 4 3 4 5% 45%	6467
	11th to 20th	Night	3 6% 4 11% 5% 5% 4 4 5% 6% 47%	6425
	21st to end	Night	2 4 2 6% 4 4 5% 3 5% 6% 58%	6974
February	1st to 10th	Night	6% 10% 4 9% 5% 5% 5% 4 4 7% 41%	2600
	11th to 20th	Night	4 10% 3 9% 4 5% 4 4 6% 6% 44%	2363
	21st to end	Night	5% 8% 3 7% 4 4 4 3 5% 6% 50%	1980
March	1st to 10th	Night	6% 8% 3 6% 4 3 4 3 5% 6% 52%	5374
	11th to 20th	Night	5% 5% 2 5% 4 4 4 4 6% 8% 53%	5299
	21st to end	Night	13% 10% 3 7% 4 4 4 4 6% 9% 36%	4984
April	1st to 10th	Night	13% 9% 3 4 4 3 4 3 7% 7% 44%	2000
	11th to 20th	Night	13% 8% 3 6% 4 4 4 3 5% 6% 44%	1977
	21st to end	Night	14% 7% 2 6% 5% 4 4 3 6% 8% 42%	1871
May	1st to 10th	Night	10% 5% 2 6% 5% 4 4 3 5% 6% 49%	3992
	11th to 20th	Night	11% 6% 2 6% 3 4 4 4 5% 8% 47%	3617
	21st to end	Night	21% 6% 2 5% 3 4 4 3 5% 6% 42%	3972
June	1st to 10th	Night	8% 4 2 5% 4 3 5% 4 7% 10% 48%	1600
	11th to 20th	Night	11% 4 1 4 4 4 4 5% 6% 8% 48%	1600
	21st to end	Night	6% 3 1 4 3 3 4 3 7% 8% 58%	1600
July	1st to 10th	Night	4 4 2 5% 4 5% 4 4 5% 9% 54%	3640
	11th to 20th	Night	6% 3 1 4 4 5% 5% 4 7% 9% 52%	3640
	21st to end	Night	7% 4 2 4 4 4 4 4 7% 9% 52%	3970
August	1st to 10th	Night	6% 3 2 5% 4 5% 5% 4 7% 9% 49%	3580
	11th to 20th	Night	4 5% 2 5% 4 5% 4 4 6% 9% 53%	4344
	21st to end	Night	5% 5% 2 7% 5% 5% 5% 4 6% 8% 48%	4993
September	1st to 10th	Night	7% 2 1 4 3 3 4 3 4 6% 64%	2000
	11th to 20th	Night	8% 3 1 4 3 4 4 3 5% 7% 58%	2085
	21st to end	Night	10% 4 1 4 3 3 2 2 3 5% 63%	2200
October	1st to 10th	Night	7% 4 1 2 2 2 2 2 2 4 72%	3750
	11th to 20th	Night	7% 5% 2 5% 3 3 3 3 5% 6% 59%	3898
	21st to end	Night	9% 6% 1 4 3 3 4 3 5% 7% 54%	4610
November	1st to 10th	Night	7% 6% 2 6% 3 3 3 4 6% 7% 53%	2665
	11th to 20th	Night	6% 5% 2 5% 4 3 4 3 6% 7% 55%	2730
	21st to end	Night	4 7% 2 5% 4 3 4 4 5% 7% 54%	2908
December	1st to 10th	Night	3 6% 2 6% 4 4 4 3 5% 7% 56%	4710
	11th to 20th	Night	2 6% 3 6% 6% 5% 5% 4 5% 7% 50%	5321
	21st to end	Night	7% 10% 3 7% 4 4 4 4 6% 6% 45%	7128

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	35% 5% 17% 28% 13% 2	3719
	11th to 20th	Day	39% 6% 13% 25% 13% 4	3688
	21st to end	Day	25% 4 16% 31% 17% 7%	4046
February	1st to 10th	Day	42% 6% 14% 22% 14% 2	1800
	11th to 20th	Day	39% 6% 15% 22% 13% 4	1933
	21st to end	Day	33% 6% 17% 26% 16% 3	1650
March	1st to 10th	Day	30% 4 8% 28% 23% 7%	4500
	11th to 20th	Day	26% 5% 15% 31% 21% 2	4666
	21st to end	Day	42% 6% 16% 24% 11%	5969
April	1st to 10th	Day	38% 6% 16% 26% 11% 4	2400
	11th to 20th	Day	41% 6% 12% 22% 17% 2	2374
	21st to end	Day	40% 5% 16% 27% 11% 1	2527
May	1st to 10th	Day	34% 6% 14% 28% 15% 2	5985
	11th to 20th	Day	38% 6% 13% 24% 16% 3	6302
	21st to end	Day	38% 6% 15% 27% 14% 1	6926
June	1st to 10th	Day	27% 8% 20% 29% 14% 2	2800
	11th to 20th	Day	28% 6% 18% 26% 16% 6%	2800
	21st to end	Day	20% 6% 13% 30% 24% 7%	2800
July	1st to 10th	Day	23% 5% 9% 32% 26% 4	6271
	11th to 20th	Day	25% 4 11% 31% 23% 7%	6265
	21st to end	Day	25% 4 10% 23% 22% 15%	6705
August	1st to 10th	Day	29% 4 16% 25% 18% 8%	4536
	11th to 20th	Day	26% 5% 14% 27% 22% 7%	3969
	21st to end	Day	21% 3 10% 22% 26% 17%	4311
September	1st to 10th	Day	21% 4 9% 27% 27% 12%	2400
	11th to 20th	Day	23% 5% 10% 27% 25% 10%	2315
	21st to end	Day	24% 3 8% 32% 26% 6%	2200
October	1st to 10th	Day	19% 3 8% 18% 33% 19%	3430
	11th to 20th	Day	25% 3 11% 37% 21% 4	3204
	21st to end	Day	32% 3 13% 29% 17% 4	3190
November	1st to 10th	Day	27% 6% 14% 28% 21% 5%	1853
	11th to 20th	Day	26% 5% 14% 31% 19% 5%	1890
	21st to end	Day	29% 5% 15% 30% 17% 3	1711
December	1st to 10th	Day	25% 4 17% 31% 21% 2	2700
	11th to 20th	Day	24% 4 19% 36% 15% 1	3104
	21st to end	Day	36% 4 8% 34% 16% 2	4092
January	1st to 10th	Night	42% 4 12% 28% 11% 3	6467
	11th to 20th	Night	36% 6% 14% 24% 15% 6%	6425
	21st to end	Night	25% 5% 17% 29% 21% 3	6974
February	1st to 10th	Night	41% 6% 16% 23% 12% 2	2600
	11th to 20th	Night	38% 7% 15% 25% 12% 3	2363
	21st to end	Night	34% 5% 13% 27% 17% 4	1980
March	1st to 10th	Night	32% 4 9% 30% 18% 6%	5374
	11th to 20th	Night	29% 5% 13% 25% 27% 1	5299
	21st to end	Night	45% 6% 18% 20% 10% 1	4984
April	1st to 10th	Night	37% 8% 14% 25% 14% 3	2000
	11th to 20th	Night	40% 6% 12% 24% 15% 3	1977
	21st to end	Night	39% 8% 15% 25% 13% 2	1871
May	1st to 10th	Night	34% 5% 12% 31% 16% 2	3992
	11th to 20th	Night	35% 6% 14% 32% 12% 3	3618
	21st to end	Night	42% 7% 12% 24% 14% 1	3972
June	1st to 10th	Night	29% 8% 23% 25% 13% 2	1600
	11th to 20th	Night	31% 8% 19% 24% 13% 4	1600
	21st to end	Night	22% 6% 16% 28% 21% 6%	1600
July	1st to 10th	Night	29% 3 13% 28% 24% 3	3600
	11th to 20th	Night	28% 3 14% 32% 18% 6%	3592
	21st to end	Night	29% 4 13% 27% 21% 6%	3856
August	1st to 10th	Night	32% 5% 18% 22% 17% 6%	2600
	11th to 20th	Night	31% 4 16% 25% 20% 4	3140
	21st to end	Night	25% 4 11% 25% 27% 9%	3597
September	1st to 10th	Night	24% 3 9% 28% 27% 9%	2000
	11th to 20th	Night	25% 5% 11% 25% 25% 8%	2085
	21st to end	Night	26% 3 6% 29% 26% 10%	2200
October	1st to 10th	Night	19% 3 7% 20% 33% 18%	3750
	11th to 20th	Night	27% 3 10% 35% 21% 4	3898
	21st to end	Night	30% 4 11% 29% 18% 8%	4610
November	1st to 10th	Night	30% 5% 15% 26% 20% 5%	2665
	11th to 20th	Night	28% 4 13% 30% 20% 5%	2730
	21st to end	Night	28% 6% 14% 29% 20% 3	2908
December	1st to 10th	Night	28% 5% 15% 32% 19% 3	4710
	11th to 20th	Night	32% 5% 17% 32% 13% 2	5322
	21st to end	Night	39% 4 10% 31% 14% 2	7128

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	6% 14% 38% 28% 11% 3	330
	11th to 20th	Day	12% 19% 36% 26% 6%	318
	21st to end	Day	10% 24% 40% 19% 6% 1	330
February	1st to 10th	Day	14% 20% 48% 17% 1	300
	11th to 20th	Day	8% 22% 46% 18% 5%	300
	21st to end	Day	8% 27% 38% 25% 2	249
March	1st to 10th	Day	8% 26% 34% 24% 7% 1	300
	11th to 20th	Day	16% 14% 34% 29% 8% 1	340
	21st to end	Day	22% 18% 29% 24% 6% 1	550
April	1st to 10th	Day	18% 21% 39% 18% 4	500
	11th to 20th	Day	21% 24% 34% 18% 3	492
	21st to end	Day	18% 15% 30% 26% 9% 1	627
May	1st to 10th	Day	16% 15% 30% 22% 13% 3	703
	11th to 20th	Day	20% 10% 25% 26% 16% 4	725
	21st to end	Day	19% 11% 26% 28% 14% 2	789
June	1st to 10th	Day	9% 8% 26% 31% 22% 4	730
	11th to 20th	Day	12% 10% 34% 31% 12% 1	730
	21st to end	Day	8% 7% 28% 36% 19% 2	730
July	1st to 10th	Day	6% 4 22% 39% 24% 4	721
	11th to 20th	Day	5% 4 30% 40% 19% 2	718
	21st to end	Day	7% 4 23% 39% 24% 3	794
August	1st to 10th	Day	6% 4 24% 43% 20% 3	726
	11th to 20th	Day	5% 5% 26% 35% 24% 5%	560
	21st to end	Day	5% 8% 28% 35% 21% 3	583
September	1st to 10th	Day	6% 7% 28% 37% 18% 4	530
	11th to 20th	Day	9% 7% 27% 32% 20% 5%	445
	21st to end	Day	12% 12% 25% 32% 16% 4	330
October	1st to 10th	Day	15% 12% 24% 26% 17% 6%	330
	11th to 20th	Day	18% 15% 35% 21% 9% 2	330
	21st to end	Day	11% 17% 34% 25% 11% 2	363
November	1st to 10th	Day	12% 17% 38% 24% 8% 2	330
	11th to 20th	Day	12% 15% 40% 27% 7%	330
	21st to end	Day	9% 14% 43% 26% 8% 1	330
December	1st to 10th	Day	11% 20% 39% 25% 5%	330
	11th to 20th	Day	11% 17% 50% 18% 3	330
	21st to end	Day	13% 18% 43% 21% 4 1	363
January	1st to 10th	Night	6% 12% 41% 30% 11%	1050
	11th to 20th	Night	6% 16% 46% 25% 7% 1	1031
	21st to end	Night	8% 13% 46% 28% 5%	1100
February	1st to 10th	Night	9% 13% 45% 27% 5% 1	800
	11th to 20th	Night	9% 11% 41% 33% 5% 1	784
	21st to end	Night	10% 11% 44% 30% 5%	660
March	1st to 10th	Night	10% 11% 38% 36% 6%	800
	11th to 20th	Night	9% 7% 35% 40% 8% 1	790
	21st to end	Night	18% 10% 30% 33% 8%	660
April	1st to 10th	Night	18% 9% 33% 37% 4	600
	11th to 20th	Night	17% 11% 33% 33% 5%	593
	21st to end	Night	17% 10% 27% 34% 11% 1	600
May	1st to 10th	Night	14% 9% 28% 35% 13% 1	600
	11th to 20th	Night	16% 7% 24% 36% 17% 1	591
	21st to end	Night	19% 7% 30% 33% 11%	650
June	1st to 10th	Night	8% 4 27% 46% 15% 1	600
	11th to 20th	Night	13% 6% 34% 39% 8% 1	600
	21st to end	Night	6% 4 27% 51% 12%	600
July	1st to 10th	Night	5% 4 22% 46% 23% 1	585
	11th to 20th	Night	5% 3 28% 50% 14%	582
	21st to end	Night	5% 2 23% 54% 16%	657
August	1st to 10th	Night	4 3 25% 51% 16% 1	597
	11th to 20th	Night	5% 4 19% 52% 20% 1	594
	21st to end	Night	5% 4 24% 46% 21% 1	660
September	1st to 10th	Night	8% 3 21% 48% 19% 1	600
	11th to 20th	Night	9% 6% 24% 41% 20% 1	600
	21st to end	Night	12% 7% 24% 39% 18%	600
October	1st to 10th	Night	14% 6% 25% 37% 17% 1	695
	11th to 20th	Night	12% 8% 29% 39% 12%	800
	21st to end	Night	12% 8% 36% 34% 9% 1	1100
November	1st to 10th	Night	10% 7% 37% 35% 8% 2	1025
	11th to 20th	Night	10% 10% 38% 35% 7%	1050
	21st to end	Night	7% 10% 38% 40% 6%	1050
December	1st to 10th	Night	7% 12% 48% 28% 6%	1050
	11th to 20th	Night	8% 9% 44% 33% 6%	1050
	21st to end	Night	11% 13% 41% 28% 7%	1155

Page generated at 2026-01-13 23:14:25. Version ac07

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