Hico
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hico clear sky chart from 2005-11-06 to 2026-04-17.

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	10% 5% 2 5% 3 3 4 3 5% 7% 54%	131837
	Night	10% 5% 2 4 3 3 3 3 4 7% 57%	130653
Transparency	Day	29% 5% 9% 22% 24% 10%	135593
	Night	27% 5% 9% 21% 24% 13%	134961
Seeing	Day	10% 7% 23% 29% 23% 8%	16877
	Night	11% 7% 29% 36% 16% 1	26918

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	9% 6% 3 5% 3 3 3 2 3 5% 59%	5289
	11th to 20th	Day	8% 5% 2 3 2 3 3 2 4 6% 63%	5310
	21st to end	Day	20% 7% 2 4 3 3 3 2 3 5% 46%	5974
February	1st to 10th	Day	13% 5% 2 6% 4 3 3 2 5% 5% 52%	2100
	11th to 20th	Day	14% 7% 2 7% 4 3 3 2 3 6% 49%	2049
	21st to end	Day	15% 7% 2 4 2 2 2 2 3 4 57%	1730
March	1st to 10th	Day	12% 5% 2 5% 4 4 4 3 5% 6% 52%	4956
	11th to 20th	Day	12% 5% 2 4 3 3 4 3 4 6% 57%	5090
	21st to end	Day	9% 5% 2 6% 4 3 4 3 6% 8% 52%	5583
April	1st to 10th	Day	11% 6% 3 6% 3 4 4 4 5% 7% 48%	2310
	11th to 20th	Day	13% 6% 2 5% 4 4 4 3 5% 6% 49%	2291
	21st to end	Day	10% 5% 2 6% 4 3 4 4 5% 6% 52%	2600
May	1st to 10th	Day	13% 6% 3 6% 4 4 4 3 5% 6% 46%	5862
	11th to 20th	Day	12% 7% 2 6% 4 4 4 4 4 6% 47%	5862
	21st to end	Day	12% 6% 2 7% 5% 4 5% 4 6% 8% 41%	6434
June	1st to 10th	Day	5% 4 2 5% 4 4 5% 3 6% 7% 55%	2600
	11th to 20th	Day	5% 4 1 4 4 4 4 3 6% 8% 57%	2600
	21st to end	Day	5% 3 1 4 4 4 4 4 6% 8% 57%	2600
July	1st to 10th	Day	10% 6% 2 7% 5% 5% 5% 4 5% 7% 43%	5900
	11th to 20th	Day	3 2 1 3 3 3 4 4 6% 10% 61%	5900
	21st to end	Day	4 3 1 4 3 4 5% 4 6% 10% 56%	6422
August	1st to 10th	Day	1 1 1 2 2 3 3 3 5% 7% 72%	4234
	11th to 20th	Day	4 3 1 3 2 3 4 3 5% 9% 64%	4006
	21st to end	Day	3 2 1 4 4 4 5% 4 6% 10% 57%	4164
September	1st to 10th	Day	9% 5% 2 6% 4 4 5% 4 5% 5% 52%	2200
	11th to 20th	Day	9% 4 2 6% 4 4 4 4 6% 7% 50%	2200
	21st to end	Day	7% 3 1 4 3 4 3 3 5% 7% 60%	2200
October	1st to 10th	Day	5% 3 2 4 3 3 4 2 4 6% 65%	2200
	11th to 20th	Day	9% 4 1 4 2 2 2 2 4 6% 64%	2034
	21st to end	Day	11% 5% 2 4 2 2 2 2 3 4 64%	2200
November	1st to 10th	Day	12% 5% 1 4 2 2 3 2 4 5% 59%	2058
	11th to 20th	Day	6% 4 1 4 3 3 3 3 5% 6% 62%	1891
	21st to end	Day	13% 7% 2 6% 3 3 2 2 4 6% 53%	1890
December	1st to 10th	Day	16% 6% 2 4 3 3 4 3 4 4 49%	3030
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 4 4 5% 48%	3481
	21st to end	Day	13% 6% 2 4 3 3 3 2 3 4 57%	4587
January	1st to 10th	Night	12% 5% 2 4 2 3 3 2 4 5% 59%	7634
	11th to 20th	Night	6% 3 1 3 2 2 3 2 3 4 71%	7680
	21st to end	Night	22% 7% 2 5% 3 3 3 3 4 5% 43%	8283
February	1st to 10th	Night	11% 6% 2 5% 3 3 3 2 4 6% 55%	2520
	11th to 20th	Night	14% 6% 3 5% 3 2 3 3 4 6% 52%	2458
	21st to end	Night	15% 5% 1 3 3 2 2 2 4 4 57%	2076
March	1st to 10th	Night	10% 6% 2 6% 4 3 4 3 5% 6% 52%	5120
	11th to 20th	Night	10% 5% 2 4 3 3 3 3 5% 7% 56%	5090
	21st to end	Night	9% 6% 2 5% 3 4 3 3 4 6% 55%	5588
April	1st to 10th	Night	8% 5% 2 4 4 3 4 3 6% 7% 54%	2310
	11th to 20th	Night	11% 5% 2 5% 4 3 4 3 5% 7% 51%	2184
	21st to end	Night	8% 6% 2 4 3 3 4 3 6% 6% 55%	1800
May	1st to 10th	Night	16% 8% 2 5% 3 4 3 3 5% 6% 46%	4053
	11th to 20th	Night	7% 7% 3 7% 4 4 4 3 5% 6% 48%	4053
	21st to end	Night	10% 5% 2 5% 4 3 4 3 6% 10% 47%	4443
June	1st to 10th	Night	3 3 1 4 3 4 4 3 5% 9% 61%	1800
	11th to 20th	Night	3 2 1 3 3 3 3 3 6% 8% 65%	1800
	21st to end	Night	3 3 1 3 3 3 3 3 6% 10% 62%	1800
July	1st to 10th	Night	9% 4 2 6% 3 4 4 4 6% 9% 50%	4078
	11th to 20th	Night	2 1 1 2 2 2 3 3 5% 11% 67%	4077
	21st to end	Night	2 3 1 4 3 4 3 4 6% 9% 60%	4449
August	1st to 10th	Night	1 1 1 1 1 1 2 4 7% 80%	2926
	11th to 20th	Night	3 3 1 3 2 2 2 3 5% 12% 65%	3047
	21st to end	Night	3 2 1 3 3 3 3 4 6% 11% 61%	3725
September	1st to 10th	Night	8% 4 2 4 4 3 3 3 6% 7% 57%	2200
	11th to 20th	Night	10% 4 2 5% 3 4 3 4 5% 7% 53%	2200
	21st to end	Night	6% 3 1 4 3 3 3 3 5% 8% 62%	2200
October	1st to 10th	Night	5% 3 1 2 2 2 3 3 4 7% 68%	2200
	11th to 20th	Night	9% 3 1 3 2 2 3 2 3 5% 66%	2345
	21st to end	Night	12% 4 2 3 2 2 2 2 3 4 63%	2640
November	1st to 10th	Night	10% 5% 1 4 3 3 3 2 3 4 63%	2460
	11th to 20th	Night	5% 4 2 5% 3 4 3 3 4 7% 62%	2725
	21st to end	Night	14% 5% 2 4 3 3 2 3 4 6% 54%	2730
December	1st to 10th	Night	15% 6% 2 5% 3 3 3 2 4 5% 53%	4380
	11th to 20th	Night	12% 7% 2 6% 4 3 3 3 4 5% 52%	4946
	21st to end	Night	12% 6% 2 4 2 2 3 2 3 4 59%	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	30% 3 6% 23% 29% 8%	5290
	11th to 20th	Day	24% 2 5% 22% 33% 13%	5310
	21st to end	Day	43% 3 4 15% 23% 12%	5974
February	1st to 10th	Day	35% 4 5% 16% 23% 16%	2100
	11th to 20th	Day	39% 3 7% 19% 20% 11%	2059
	21st to end	Day	34% 3 3 15% 26% 18%	1730
March	1st to 10th	Day	33% 5% 7% 14% 22% 20%	4956
	11th to 20th	Day	30% 5% 10% 11% 17% 27%	5090
	21st to end	Day	30% 6% 10% 22% 21% 10%	5585
April	1st to 10th	Day	35% 6% 10% 18% 19% 13%	2310
	11th to 20th	Day	36% 5% 8% 18% 21% 11%	2291
	21st to end	Day	33% 6% 9% 19% 25% 8%	2600
May	1st to 10th	Day	38% 7% 10% 20% 20% 4	5900
	11th to 20th	Day	38% 5% 8% 16% 26% 7%	5866
	21st to end	Day	39% 8% 11% 23% 14% 5%	6447
June	1st to 10th	Day	25% 8% 13% 29% 20% 4	2600
	11th to 20th	Day	24% 6% 14% 30% 20% 7%	2600
	21st to end	Day	23% 8% 14% 25% 24% 6%	2600
July	1st to 10th	Day	39% 7% 15% 29% 10% 1	5836
	11th to 20th	Day	18% 6% 18% 34% 21% 3	5831
	21st to end	Day	22% 8% 15% 32% 22% 1	6240
August	1st to 10th	Day	11% 5% 11% 33% 37% 3	4220
	11th to 20th	Day	18% 5% 15% 38% 23% 2	4045
	21st to end	Day	21% 9% 17% 31% 19% 2	4163
September	1st to 10th	Day	34% 6% 10% 18% 23% 10%	2200
	11th to 20th	Day	32% 8% 11% 21% 20% 8%	2200
	21st to end	Day	24% 4 10% 22% 27% 14%	2200
October	1st to 10th	Day	13% 3 7% 14% 33% 31%	3590
	11th to 20th	Day	16% 3 7% 20% 33% 21%	3287
	21st to end	Day	20% 3 4 23% 35% 15%	3538
November	1st to 10th	Day	30% 4 7% 19% 27% 13%	2058
	11th to 20th	Day	24% 4 8% 22% 27% 16%	1891
	21st to end	Day	36% 4 4 20% 23% 13%	1890
December	1st to 10th	Day	39% 3 5% 19% 24% 9%	3030
	11th to 20th	Day	38% 5% 7% 11% 27% 12%	3479
	21st to end	Day	32% 3 5% 19% 27% 15%	4587
January	1st to 10th	Night	30% 3 6% 19% 31% 11%	7635
	11th to 20th	Night	19% 2 4 19% 34% 22%	7680
	21st to end	Night	46% 4 3 12% 22% 13%	8283
February	1st to 10th	Night	33% 5% 6% 14% 24% 18%	2520
	11th to 20th	Night	36% 2 7% 17% 25% 13%	2458
	21st to end	Night	32% 3 6% 15% 23% 21%	2076
March	1st to 10th	Night	33% 5% 7% 15% 22% 18%	5120
	11th to 20th	Night	29% 5% 8% 15% 16% 26%	5090
	21st to end	Night	31% 6% 9% 18% 26% 11%	5588
April	1st to 10th	Night	29% 5% 9% 21% 19% 16%	2310
	11th to 20th	Night	33% 6% 10% 16% 21% 14%	2184
	21st to end	Night	29% 7% 11% 19% 26% 9%	1800
May	1st to 10th	Night	39% 7% 8% 24% 15% 7%	4080
	11th to 20th	Night	35% 7% 12% 15% 20% 11%	4054
	21st to end	Night	31% 8% 14% 27% 12% 8%	4452
June	1st to 10th	Night	21% 6% 16% 32% 20% 5%	1800
	11th to 20th	Night	17% 6% 16% 30% 24% 7%	1800
	21st to end	Night	19% 7% 12% 30% 25% 7%	1800
July	1st to 10th	Night	31% 6% 16% 35% 11% 1	4035
	11th to 20th	Night	12% 6% 17% 37% 24% 3	4026
	21st to end	Night	20% 8% 16% 32% 23% 2	4320
August	1st to 10th	Night	5% 3 12% 35% 39% 6%	2916
	11th to 20th	Night	15% 3 18% 40% 22% 3	3074
	21st to end	Night	17% 7% 20% 33% 20% 3	3725
September	1st to 10th	Night	27% 5% 12% 22% 23% 11%	2200
	11th to 20th	Night	30% 6% 12% 22% 22% 8%	2200
	21st to end	Night	21% 5% 8% 25% 24% 17%	2200
October	1st to 10th	Night	11% 2 6% 16% 26% 39%	3590
	11th to 20th	Night	15% 2 8% 18% 33% 24%	3818
	21st to end	Night	20% 3 4 21% 37% 16%	4252
November	1st to 10th	Night	27% 4 6% 20% 27% 16%	2460
	11th to 20th	Night	24% 5% 7% 22% 25% 18%	2725
	21st to end	Night	33% 3 7% 17% 25% 14%	2730
December	1st to 10th	Night	35% 3 6% 19% 25% 12%	4380
	11th to 20th	Night	37% 3 6% 11% 27% 16%	4947
	21st to end	Night	31% 3 5% 18% 24% 18%	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	12% 15% 42% 24% 7%	330
	11th to 20th	Day	14% 14% 36% 24% 10% 1	330
	21st to end	Day	16% 14% 39% 25% 6% 1	363
February	1st to 10th	Day	18% 14% 37% 25% 7%	330
	11th to 20th	Day	19% 16% 40% 21% 4	330
	21st to end	Day	22% 14% 40% 19% 4 1	273
March	1st to 10th	Day	15% 15% 38% 26% 5%	330
	11th to 20th	Day	15% 16% 39% 23% 5% 2	330
	21st to end	Day	10% 13% 42% 28% 6% 1	363
April	1st to 10th	Day	17% 14% 39% 22% 7% 1	330
	11th to 20th	Day	14% 17% 40% 23% 6%	361
	21st to end	Day	13% 12% 41% 25% 8% 1	700
May	1st to 10th	Day	13% 11% 38% 31% 7% 1	703
	11th to 20th	Day	17% 6% 30% 29% 15% 3	725
	21st to end	Day	13% 4 30% 35% 15% 3	789
June	1st to 10th	Day	5% 2 18% 40% 26% 8%	730
	11th to 20th	Day	5% 1 18% 45% 25% 5%	730
	21st to end	Day	4 1 12% 35% 37% 13%	730
July	1st to 10th	Day	7% 1 8% 32% 37% 15%	721
	11th to 20th	Day	2 1 5% 31% 46% 16%	718
	21st to end	Day	3 1 6% 26% 45% 18%	794
August	1st to 10th	Day	2 3 30% 46% 19%	726
	11th to 20th	Day	7% 1 7% 28% 40% 17%	615
	21st to end	Day	5% 1 6% 24% 36% 29%	500
September	1st to 10th	Day	9% 2 5% 22% 38% 25%	330
	11th to 20th	Day	3 1 4 19% 47% 25%	330
	21st to end	Day	10% 1 8% 26% 35% 19%	330
October	1st to 10th	Day	3 2 9% 35% 36% 15%	330
	11th to 20th	Day	9% 4 26% 30% 25% 5%	330
	21st to end	Day	18% 12% 23% 24% 19% 3	363
November	1st to 10th	Day	18% 6% 27% 28% 16% 5%	330
	11th to 20th	Day	9% 10% 30% 32% 16% 4	330
	21st to end	Day	17% 14% 34% 24% 11% 2	330
December	1st to 10th	Day	15% 9% 35% 25% 13% 2	330
	11th to 20th	Day	14% 11% 39% 24% 11% 2	330
	21st to end	Day	15% 11% 35% 29% 9% 1	363
January	1st to 10th	Night	13% 9% 40% 32% 7%	1050
	11th to 20th	Night	14% 11% 35% 33% 7%	1050
	21st to end	Night	17% 12% 35% 30% 6%	1114
February	1st to 10th	Night	14% 10% 41% 29% 6%	840
	11th to 20th	Night	17% 12% 41% 28% 3	824
	21st to end	Night	18% 13% 46% 21% 2	692
March	1st to 10th	Night	15% 14% 39% 27% 4	673
	11th to 20th	Night	15% 10% 41% 29% 5%	630
	21st to end	Night	9% 12% 44% 32% 3	693
April	1st to 10th	Night	11% 12% 45% 28% 5%	630
	11th to 20th	Night	13% 10% 45% 27% 5%	611
	21st to end	Night	10% 9% 47% 26% 8%	600
May	1st to 10th	Night	10% 10% 42% 34% 4	600
	11th to 20th	Night	10% 5% 37% 34% 13%	591
	21st to end	Night	9% 3 32% 41% 13% 1	650
June	1st to 10th	Night	4 2 20% 50% 23% 2	600
	11th to 20th	Night	4 1 25% 53% 17%	600
	21st to end	Night	3 2 16% 48% 29% 3	600
July	1st to 10th	Night	6% 1 9% 49% 31% 4	585
	11th to 20th	Night	3 1 8% 51% 35% 2	582
	21st to end	Night	1 6% 50% 40% 2	657
August	1st to 10th	Night	2 4 50% 41% 3	597
	11th to 20th	Night	7% 1 6% 45% 38% 4	594
	21st to end	Night	5% 1 3 41% 45% 6%	660
September	1st to 10th	Night	7% 1 8% 44% 36% 4	600
	11th to 20th	Night	11% 1 8% 42% 36% 3	600
	21st to end	Night	8% 1 13% 41% 35% 3	600
October	1st to 10th	Night	6% 18% 44% 29% 3	600
	11th to 20th	Night	10% 4 26% 41% 18% 1	745
	21st to end	Night	14% 8% 30% 32% 15% 1	880
November	1st to 10th	Night	11% 3 29% 41% 16% 1	820
	11th to 20th	Night	6% 7% 33% 40% 14% 1	1045
	21st to end	Night	15% 9% 36% 29% 10% 1	1050
December	1st to 10th	Night	13% 7% 35% 37% 7%	1050
	11th to 20th	Night	17% 9% 32% 34% 7% 1	1050
	21st to end	Night	15% 9% 37% 31% 8%	1155

Page generated at 2026-04-14 01:44:30. Version ac07

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