Hondo
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hondo 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	13% 6% 2 5% 4 4 4 3 5% 7% 48%	131984
	Night	14% 5% 2 4 3 3 3 3 5% 7% 52%	130507
Transparency	Day	35% 5% 10% 21% 18% 11%	135815
	Night	32% 5% 11% 20% 19% 13%	134740
Seeing	Day	14% 4 18% 30% 26% 8%	16537
	Night	15% 4 22% 40% 18% 1	26626

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% 6% 2 4 2 2 3 2 4 5% 57%	5289
	11th to 20th	Day	15% 5% 2 5% 3 2 3 2 4 4 56%	5448
	21st to end	Day	24% 8% 2 3 2 2 3 2 4 6% 44%	6468
February	1st to 10th	Day	18% 9% 2 5% 4 3 3 3 4 4 47%	2100
	11th to 20th	Day	18% 6% 2 6% 3 3 4 2 4 5% 45%	2049
	21st to end	Day	16% 6% 2 4 3 2 3 3 3 6% 52%	1730
March	1st to 10th	Day	14% 6% 2 4 2 2 3 2 4 6% 55%	4855
	11th to 20th	Day	15% 6% 2 6% 3 3 2 2 3 4 53%	5090
	21st to end	Day	19% 7% 2 5% 3 3 3 2 4 6% 47%	5583
April	1st to 10th	Day	15% 7% 2 5% 4 4 4 3 5% 6% 45%	2310
	11th to 20th	Day	18% 6% 2 5% 4 3 4 4 5% 5% 45%	2346
	21st to end	Day	16% 7% 2 6% 4 4 3 3 4 5% 44%	2450
May	1st to 10th	Day	21% 7% 2 6% 4 4 4 4 5% 8% 36%	5862
	11th to 20th	Day	10% 5% 2 5% 4 4 4 4 6% 9% 49%	5862
	21st to end	Day	13% 7% 2 7% 4 5% 5% 4 6% 8% 38%	6434
June	1st to 10th	Day	6% 4 2 4 5% 5% 5% 4 7% 9% 49%	2600
	11th to 20th	Day	6% 5% 2 5% 5% 5% 5% 5% 7% 8% 48%	2600
	21st to end	Day	8% 5% 2 7% 6% 6% 5% 4 6% 10% 42%	2600
July	1st to 10th	Day	14% 7% 3 7% 4 4 4 4 5% 8% 40%	5900
	11th to 20th	Day	8% 4 2 6% 5% 5% 5% 4 6% 11% 44%	5900
	21st to end	Day	7% 5% 2 6% 5% 5% 5% 5% 7% 11% 45%	6422
August	1st to 10th	Day	2 2 1 2 3 3 3 3 5% 8% 70%	3924
	11th to 20th	Day	4 2 1 3 3 3 4 4 7% 10% 60%	3846
	21st to end	Day	5% 3 1 5% 5% 5% 5% 4 7% 11% 50%	4223
September	1st to 10th	Day	11% 7% 3 7% 5% 5% 4 5% 7% 7% 41%	2200
	11th to 20th	Day	11% 5% 2 7% 5% 5% 5% 5% 7% 8% 43%	2200
	21st to end	Day	8% 5% 2 5% 4 5% 5% 5% 6% 8% 48%	2200
October	1st to 10th	Day	7% 4 1 5% 4 3 4 4 5% 7% 56%	2200
	11th to 20th	Day	14% 4 2 4 3 4 4 3 3 6% 53%	2153
	21st to end	Day	12% 5% 2 4 2 2 2 2 4 5% 60%	2200
November	1st to 10th	Day	17% 8% 2 6% 2 2 3 3 4 6% 47%	2058
	11th to 20th	Day	15% 6% 2 5% 3 3 3 4 4 6% 50%	1894
	21st to end	Day	19% 6% 2 5% 4 4 3 2 3 5% 46%	1890
December	1st to 10th	Day	29% 8% 3 6% 3 3 2 2 4 4 36%	3030
	11th to 20th	Day	17% 7% 2 6% 4 4 3 3 4 4 44%	3481
	21st to end	Day	14% 6% 1 4 3 3 2 2 3 4 58%	4587
January	1st to 10th	Night	14% 5% 1 4 3 2 2 2 4 6% 57%	7634
	11th to 20th	Night	12% 4 1 3 2 2 3 3 3 4 63%	7583
	21st to end	Night	28% 5% 2 4 3 2 3 2 3 4 44%	7746
February	1st to 10th	Night	15% 5% 1 5% 3 2 3 2 3 6% 54%	2520
	11th to 20th	Night	19% 6% 2 3 3 2 3 2 4 5% 51%	2458
	21st to end	Night	16% 5% 2 4 3 2 3 3 5% 6% 50%	2076
March	1st to 10th	Night	15% 7% 2 5% 4 3 3 3 5% 6% 47%	5224
	11th to 20th	Night	13% 6% 2 5% 3 3 3 2 3 5% 55%	5090
	21st to end	Night	18% 7% 1 3 3 3 3 3 4 5% 49%	5588
April	1st to 10th	Night	12% 6% 2 5% 4 3 4 3 4 7% 49%	2310
	11th to 20th	Night	16% 6% 2 5% 4 2 3 3 5% 5% 48%	2131
	21st to end	Night	17% 7% 2 5% 3 3 3 3 3 6% 47%	1949
May	1st to 10th	Night	23% 7% 2 5% 4 3 3 3 4 5% 40%	4053
	11th to 20th	Night	9% 5% 1 4 3 4 4 3 6% 8% 52%	4053
	21st to end	Night	12% 5% 2 7% 4 4 4 3 6% 9% 42%	4443
June	1st to 10th	Night	5% 2 2 3 2 3 4 3 5% 10% 61%	1800
	11th to 20th	Night	5% 3 1 4 3 3 4 3 7% 8% 58%	1800
	21st to end	Night	7% 4 2 4 3 4 3 5% 6% 9% 54%	1800
July	1st to 10th	Night	9% 6% 2 6% 5% 4 4 4 6% 9% 44%	4078
	11th to 20th	Night	4 4 2 5% 3 4 4 4 7% 11% 51%	4077
	21st to end	Night	7% 5% 2 5% 4 4 4 4 7% 8% 50%	4449
August	1st to 10th	Night	1 2 2 2 2 3 2 5% 7% 73%	3216
	11th to 20th	Night	3 2 1 3 3 3 4 3 6% 10% 62%	3213
	21st to end	Night	4 4 2 4 3 3 4 4 6% 11% 56%	3680
September	1st to 10th	Night	9% 6% 2 6% 4 5% 5% 3 6% 8% 47%	2200
	11th to 20th	Night	10% 5% 2 6% 5% 4 4 4 6% 9% 45%	2200
	21st to end	Night	7% 5% 2 5% 4 4 4 4 6% 8% 51%	2200
October	1st to 10th	Night	6% 3 1 4 3 3 4 3 4 7% 62%	2200
	11th to 20th	Night	12% 5% 2 3 3 3 4 3 4 6% 57%	2225
	21st to end	Night	14% 4 1 3 2 2 2 2 3 4 64%	2640
November	1st to 10th	Night	14% 5% 2 5% 3 3 2 2 4 5% 56%	2460
	11th to 20th	Night	11% 4 2 4 4 3 4 3 5% 6% 55%	2722
	21st to end	Night	18% 5% 1 4 3 3 3 3 4 6% 49%	2730
December	1st to 10th	Night	31% 7% 2 5% 2 2 2 2 4 5% 38%	4380
	11th to 20th	Night	21% 8% 2 5% 3 2 3 2 3 4 47%	4946
	21st to end	Night	16% 5% 2 3 2 2 2 2 3 6% 56%	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	32% 2 6% 22% 24% 14%	5290
	11th to 20th	Day	34% 1 4 14% 25% 23%	5448
	21st to end	Day	43% 3 5% 15% 24% 10%	6468
February	1st to 10th	Day	41% 4 6% 12% 20% 18%	2100
	11th to 20th	Day	41% 3 6% 17% 19% 13%	2059
	21st to end	Day	35% 4 6% 17% 22% 15%	1730
March	1st to 10th	Day	33% 3 6% 18% 16% 24%	4855
	11th to 20th	Day	36% 4 5% 9% 15% 32%	5090
	21st to end	Day	39% 4 7% 19% 18% 13%	5585
April	1st to 10th	Day	40% 5% 8% 15% 18% 14%	2310
	11th to 20th	Day	40% 5% 8% 18% 16% 13%	2346
	21st to end	Day	42% 5% 6% 18% 17% 12%	2450
May	1st to 10th	Day	46% 6% 9% 18% 14% 6%	5900
	11th to 20th	Day	30% 6% 13% 22% 18% 10%	5866
	21st to end	Day	39% 8% 10% 28% 14% 1	6447
June	1st to 10th	Day	27% 10% 15% 27% 19% 3	2600
	11th to 20th	Day	31% 8% 12% 26% 18% 5%	2600
	21st to end	Day	35% 8% 14% 26% 14% 3	2600
July	1st to 10th	Day	42% 6% 15% 29% 6% 1	5836
	11th to 20th	Day	33% 8% 17% 29% 12% 1	5831
	21st to end	Day	31% 7% 17% 27% 16% 2	6240
August	1st to 10th	Day	13% 5% 11% 43% 27% 1	3910
	11th to 20th	Day	18% 7% 23% 40% 11% 2	3882
	21st to end	Day	27% 9% 19% 24% 19% 2	4222
September	1st to 10th	Day	40% 8% 11% 19% 16% 7%	2200
	11th to 20th	Day	37% 8% 12% 20% 18% 5%	2200
	21st to end	Day	31% 7% 10% 22% 17% 12%	2200
October	1st to 10th	Day	18% 3 7% 12% 25% 35%	3590
	11th to 20th	Day	27% 5% 7% 18% 20% 22%	3484
	21st to end	Day	26% 4 6% 15% 34% 15%	3538
November	1st to 10th	Day	39% 4 8% 19% 17% 13%	2058
	11th to 20th	Day	35% 4 8% 16% 19% 17%	1894
	21st to end	Day	42% 3 5% 16% 20% 13%	1890
December	1st to 10th	Day	54% 3 4 14% 14% 11%	3030
	11th to 20th	Day	42% 6% 6% 14% 18% 14%	3479
	21st to end	Day	32% 3 4 16% 29% 16%	4587
January	1st to 10th	Night	31% 3 7% 19% 24% 17%	7635
	11th to 20th	Night	27% 1 4 16% 27% 24%	7583
	21st to end	Night	46% 2 3 13% 22% 13%	7746
February	1st to 10th	Night	33% 4 7% 14% 21% 21%	2520
	11th to 20th	Night	37% 3 6% 18% 19% 16%	2458
	21st to end	Night	35% 5% 8% 15% 21% 17%	2076
March	1st to 10th	Night	38% 4 7% 17% 16% 18%	5224
	11th to 20th	Night	33% 5% 6% 13% 15% 28%	5090
	21st to end	Night	36% 5% 11% 19% 17% 12%	5588
April	1st to 10th	Night	35% 5% 11% 18% 16% 15%	2310
	11th to 20th	Night	38% 5% 11% 14% 16% 16%	2131
	21st to end	Night	40% 6% 10% 18% 15% 12%	1949
May	1st to 10th	Night	45% 6% 9% 17% 15% 9%	4080
	11th to 20th	Night	30% 7% 11% 20% 19% 13%	4054
	21st to end	Night	37% 8% 13% 28% 12% 2	4452
June	1st to 10th	Night	19% 7% 20% 31% 21% 3	1800
	11th to 20th	Night	22% 6% 13% 31% 24% 5%	1800
	21st to end	Night	26% 9% 21% 27% 15% 3	1800
July	1st to 10th	Night	36% 8% 24% 27% 5% 1	4035
	11th to 20th	Night	26% 8% 23% 30% 12% 1	4026
	21st to end	Night	30% 8% 21% 25% 13% 3	4320
August	1st to 10th	Night	11% 6% 15% 44% 23% 1	3206
	11th to 20th	Night	17% 7% 30% 37% 8% 1	3243
	21st to end	Night	23% 11% 23% 24% 17% 2	3680
September	1st to 10th	Night	34% 7% 15% 21% 16% 7%	2200
	11th to 20th	Night	34% 9% 15% 22% 15% 5%	2200
	21st to end	Night	28% 7% 14% 24% 16% 12%	2200
October	1st to 10th	Night	15% 4 7% 17% 21% 36%	3590
	11th to 20th	Night	21% 4 10% 16% 26% 22%	3620
	21st to end	Night	23% 3 7% 18% 32% 17%	4252
November	1st to 10th	Night	32% 4 7% 19% 23% 16%	2460
	11th to 20th	Night	30% 5% 9% 18% 21% 17%	2722
	21st to end	Night	36% 5% 8% 17% 19% 15%	2730
December	1st to 10th	Night	52% 3 6% 14% 13% 13%	4380
	11th to 20th	Night	41% 4 6% 12% 19% 18%	4947
	21st to end	Night	31% 4 5% 14% 27% 19%	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% 7% 28% 31% 12% 1	330
	11th to 20th	Day	20% 8% 26% 32% 14% 2	330
	21st to end	Day	21% 5% 33% 31% 10% 1	363
February	1st to 10th	Day	28% 7% 24% 25% 15% 2	330
	11th to 20th	Day	23% 7% 34% 26% 9% 1	330
	21st to end	Day	24% 6% 35% 27% 8%	273
March	1st to 10th	Day	22% 9% 34% 29% 5%	330
	11th to 20th	Day	15% 6% 39% 28% 10% 2	330
	21st to end	Day	17% 8% 35% 29% 10% 1	363
April	1st to 10th	Day	21% 8% 33% 28% 10%	330
	11th to 20th	Day	16% 10% 35% 28% 10% 1	416
	21st to end	Day	18% 7% 34% 35% 5% 1	550
May	1st to 10th	Day	22% 4 30% 33% 11%	703
	11th to 20th	Day	18% 4 26% 37% 13% 2	725
	21st to end	Day	19% 4 24% 34% 18% 1	789
June	1st to 10th	Day	8% 2 13% 40% 32% 5%	730
	11th to 20th	Day	8% 2 12% 44% 30% 4	730
	21st to end	Day	9% 2 7% 34% 37% 11%	730
July	1st to 10th	Day	14% 2 4 28% 39% 13%	721
	11th to 20th	Day	6% 2 3 27% 49% 13%	718
	21st to end	Day	5% 2 4 25% 45% 18%	794
August	1st to 10th	Day	2 1 2 28% 45% 23%	546
	11th to 20th	Day	5% 1 3 26% 44% 21%	517
	21st to end	Day	6% 2 4 21% 40% 28%	533
September	1st to 10th	Day	11% 2 2 22% 34% 29%	330
	11th to 20th	Day	6% 1 3 16% 45% 29%	330
	21st to end	Day	8% 1 3 22% 45% 22%	330
October	1st to 10th	Day	6% 7% 25% 45% 17%	330
	11th to 20th	Day	11% 2 8% 36% 34% 10%	330
	21st to end	Day	15% 7% 18% 28% 25% 8%	363
November	1st to 10th	Day	21% 2 17% 29% 22% 9%	330
	11th to 20th	Day	20% 4 17% 32% 21% 7%	330
	21st to end	Day	24% 7% 27% 27% 13% 2	330
December	1st to 10th	Day	24% 6% 18% 31% 18% 3	330
	11th to 20th	Day	24% 8% 18% 31% 18% 1	330
	21st to end	Day	20% 4 23% 33% 17% 2	363
January	1st to 10th	Night	19% 4 24% 40% 12% 1	1050
	11th to 20th	Night	19% 7% 25% 41% 8%	1018
	21st to end	Night	23% 5% 25% 37% 10%	924
February	1st to 10th	Night	19% 7% 26% 38% 9%	840
	11th to 20th	Night	24% 7% 29% 33% 7%	824
	21st to end	Night	21% 5% 37% 34% 3	692
March	1st to 10th	Night	22% 8% 34% 31% 5%	726
	11th to 20th	Night	19% 7% 33% 34% 6%	630
	21st to end	Night	17% 6% 38% 33% 5%	693
April	1st to 10th	Night	15% 8% 40% 34% 3	630
	11th to 20th	Night	18% 8% 42% 29% 3	611
	21st to end	Night	22% 7% 38% 28% 6%	600
May	1st to 10th	Night	16% 6% 42% 32% 5%	600
	11th to 20th	Night	15% 5% 33% 39% 8%	591
	21st to end	Night	14% 3 35% 38% 10%	650
June	1st to 10th	Night	7% 2 23% 49% 19% 1	600
	11th to 20th	Night	7% 2 25% 52% 14% 1	600
	21st to end	Night	8% 1 14% 49% 27% 1	600
July	1st to 10th	Night	11% 2 6% 49% 30% 2	585
	11th to 20th	Night	4 1 9% 50% 33% 3	582
	21st to end	Night	5% 2 7% 46% 39% 2	657
August	1st to 10th	Night	2 7% 46% 42% 2	597
	11th to 20th	Night	5% 1 5% 48% 38% 3	594
	21st to end	Night	6% 2 5% 37% 45% 4	660
September	1st to 10th	Night	10% 2 4 45% 34% 6%	600
	11th to 20th	Night	11% 2 6% 40% 38% 4	600
	21st to end	Night	8% 1 8% 44% 35% 4	600
October	1st to 10th	Night	7% 1 7% 50% 33% 2	600
	11th to 20th	Night	14% 1 16% 42% 24% 2	625
	21st to end	Night	15% 3 20% 35% 25% 2	880
November	1st to 10th	Night	14% 3 17% 39% 25% 2	820
	11th to 20th	Night	13% 3 18% 44% 21% 2	1042
	21st to end	Night	20% 4 21% 38% 15% 1	1050
December	1st to 10th	Night	22% 4 20% 39% 14% 2	1050
	11th to 20th	Night	25% 5% 19% 39% 11% 1	1050
	21st to end	Night	19% 5% 20% 43% 12% 1	1155

Page generated at 2026-04-14 01:44:27. Version ac07

Copyright © 2026 Attilla Danko.