Edinburg
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Edinburg clear sky chart from 2005-11-06 to 2026-02-01.

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
Transparency	Day	33% 8% 14% 23% 15% 7%	131321
	Night	34% 7% 16% 22% 14% 7%	129034
Seeing	Day	10% 4 20% 34% 23% 8%	15866
	Night	13% 4 23% 38% 20% 2	25978

By Month

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	41% 7% 10% 17% 16% 9%	4168
	11th to 20th	Day	40% 6% 10% 21% 16% 8%	4387
	21st to end	Day	49% 7% 8% 14% 16% 5%	5104
February	1st to 10th	Day	40% 4 9% 16% 17% 13%	2000
	11th to 20th	Day	38% 5% 11% 20% 18% 9%	1959
	21st to end	Day	35% 5% 9% 21% 19% 10%	1669
March	1st to 10th	Day	35% 7% 11% 20% 10% 17%	4936
	11th to 20th	Day	37% 5% 7% 10% 23% 17%	4980
	21st to end	Day	30% 5% 9% 26% 16% 13%	5464
April	1st to 10th	Day	34% 7% 11% 21% 17% 11%	2200
	11th to 20th	Day	36% 8% 12% 21% 15% 9%	2176
	21st to end	Day	33% 9% 12% 20% 17% 9%	2286
May	1st to 10th	Day	35% 10% 16% 24% 11% 4	5900
	11th to 20th	Day	24% 8% 13% 27% 19% 10%	5866
	21st to end	Day	28% 8% 13% 35% 16% 1	6447
June	1st to 10th	Day	24% 8% 14% 31% 20% 3	2600
	11th to 20th	Day	25% 8% 14% 24% 24% 4	2600
	21st to end	Day	34% 11% 20% 24% 10% 1	2600
July	1st to 10th	Day	41% 9% 22% 24% 4	5836
	11th to 20th	Day	30% 9% 28% 24% 8%	5831
	21st to end	Day	31% 8% 22% 31% 8%	6162
August	1st to 10th	Day	12% 6% 21% 45% 15%	3892
	11th to 20th	Day	22% 10% 34% 28% 6%	3882
	21st to end	Day	26% 11% 24% 29% 10% 1	4014
September	1st to 10th	Day	42% 10% 16% 18% 11% 2	2200
	11th to 20th	Day	44% 13% 16% 17% 8% 3	2200
	21st to end	Day	33% 10% 15% 23% 13% 6%	2200
October	1st to 10th	Day	25% 6% 8% 14% 27% 21%	3590
	11th to 20th	Day	26% 7% 10% 18% 24% 16%	3445
	21st to end	Day	22% 6% 9% 22% 28% 12%	3538
November	1st to 10th	Day	31% 7% 11% 22% 21% 9%	2058
	11th to 20th	Day	39% 5% 8% 20% 19% 9%	2100
	21st to end	Day	38% 4 11% 19% 17% 10%	1935
December	1st to 10th	Day	58% 4 8% 15% 10% 4	3030
	11th to 20th	Day	40% 9% 11% 16% 12% 12%	3479
	21st to end	Day	34% 6% 7% 23% 19% 11%	4587
January	1st to 10th	Night	42% 5% 10% 17% 16% 11%	6018
	11th to 20th	Night	43% 6% 9% 17% 16% 9%	5842
	21st to end	Night	54% 5% 10% 13% 12% 5%	6116
February	1st to 10th	Night	41% 6% 9% 17% 13% 14%	2400
	11th to 20th	Night	41% 6% 10% 18% 16% 8%	2338
	21st to end	Night	38% 5% 10% 18% 20% 9%	1960
March	1st to 10th	Night	39% 6% 11% 20% 12% 12%	4919
	11th to 20th	Night	39% 7% 9% 12% 16% 18%	4980
	21st to end	Night	34% 5% 10% 22% 21% 9%	5467
April	1st to 10th	Night	37% 7% 16% 19% 13% 7%	2200
	11th to 20th	Night	40% 8% 12% 17% 13% 9%	2173
	21st to end	Night	42% 10% 12% 17% 13% 7%	2104
May	1st to 10th	Night	46% 10% 15% 17% 8% 3	4080
	11th to 20th	Night	32% 9% 14% 23% 16% 6%	4054
	21st to end	Night	37% 9% 18% 30% 6%	4452
June	1st to 10th	Night	18% 8% 20% 32% 19% 2	1800
	11th to 20th	Night	22% 8% 13% 34% 21% 3	1800
	21st to end	Night	25% 10% 25% 29% 10% 1	1800
July	1st to 10th	Night	40% 10% 27% 21% 3	4035
	11th to 20th	Night	31% 10% 33% 23% 4	4026
	21st to end	Night	26% 8% 30% 29% 7%	4379
August	1st to 10th	Night	7% 5% 28% 52% 9%	3244
	11th to 20th	Night	19% 8% 41% 29% 3	3243
	21st to end	Night	15% 9% 34% 32% 9% 1	3884
September	1st to 10th	Night	31% 10% 23% 25% 10% 1	2200
	11th to 20th	Night	32% 11% 21% 25% 10% 2	2200
	21st to end	Night	25% 10% 18% 30% 13% 5%	2200
October	1st to 10th	Night	17% 5% 9% 19% 28% 22%	3590
	11th to 20th	Night	23% 5% 11% 20% 25% 16%	3658
	21st to end	Night	25% 5% 8% 22% 30% 10%	4252
November	1st to 10th	Night	28% 6% 12% 22% 24% 9%	2460
	11th to 20th	Night	35% 6% 12% 21% 17% 9%	2520
	21st to end	Night	37% 5% 14% 20% 15% 9%	2680
December	1st to 10th	Night	59% 5% 7% 12% 13% 4	4380
	11th to 20th	Night	37% 7% 11% 22% 12% 11%	4947
	21st to end	Night	35% 5% 9% 18% 18% 14%	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	19% 7% 29% 26% 16% 3	330
	11th to 20th	Day	18% 9% 29% 31% 9% 3	330
	21st to end	Day	23% 9% 33% 24% 10% 1	363
February	1st to 10th	Day	13% 8% 32% 27% 18% 1	300
	11th to 20th	Day	20% 7% 37% 27% 8% 1	300
	21st to end	Day	15% 6% 39% 31% 7% 1	249
March	1st to 10th	Day	15% 8% 33% 32% 12% 1	300
	11th to 20th	Day	17% 7% 36% 30% 8% 1	300
	21st to end	Day	9% 10% 42% 33% 6%	330
April	1st to 10th	Day	12% 9% 35% 32% 10% 1	300
	11th to 20th	Day	8% 12% 33% 33% 12% 3	294
	21st to end	Day	10% 8% 41% 31% 9% 1	386
May	1st to 10th	Day	11% 5% 40% 31% 11% 1	703
	11th to 20th	Day	8% 6% 38% 34% 12% 1	725
	21st to end	Day	5% 4 30% 42% 17% 2	789
June	1st to 10th	Day	3 1 15% 40% 32% 8%	730
	11th to 20th	Day	5% 1 15% 48% 25% 6%	730
	21st to end	Day	6% 1 13% 42% 27% 11%	730
July	1st to 10th	Day	8% 2 10% 38% 33% 9%	721
	11th to 20th	Day	4 1 6% 42% 37% 10%	718
	21st to end	Day	5% 1 5% 41% 37% 12%	765
August	1st to 10th	Day	2 1 5% 45% 35% 14%	527
	11th to 20th	Day	2 1 4 44% 34% 15%	517
	21st to end	Day	2 1 6% 23% 36% 32%	403
September	1st to 10th	Day	12% 2 4 22% 37% 23%	330
	11th to 20th	Day	8% 1 5% 19% 33% 34%	330
	21st to end	Day	6% 1 7% 21% 42% 24%	330
October	1st to 10th	Day	8% 2 6% 23% 36% 25%	330
	11th to 20th	Day	9% 1 7% 28% 36% 19%	330
	21st to end	Day	10% 4 18% 32% 28% 7%	363
November	1st to 10th	Day	12% 4 12% 34% 31% 7%	330
	11th to 20th	Day	22% 4 14% 25% 25% 10%	330
	21st to end	Day	24% 8% 26% 21% 13% 9%	330
December	1st to 10th	Day	25% 4 22% 24% 18% 7%	330
	11th to 20th	Day	17% 8% 24% 26% 20% 5%	330
	21st to end	Day	20% 4 21% 33% 18% 4	363
January	1st to 10th	Night	21% 7% 26% 34% 12%	1050
	11th to 20th	Night	22% 6% 26% 37% 8%	966
	21st to end	Night	23% 5% 27% 36% 9%	924
February	1st to 10th	Night	21% 5% 33% 34% 6%	800
	11th to 20th	Night	22% 7% 35% 32% 5%	784
	21st to end	Night	20% 5% 42% 26% 6%	640
March	1st to 10th	Night	17% 10% 35% 33% 5%	600
	11th to 20th	Night	16% 8% 42% 29% 6%	600
	21st to end	Night	13% 7% 46% 30% 3	660
April	1st to 10th	Night	14% 6% 46% 30% 5%	600
	11th to 20th	Night	15% 9% 39% 32% 5%	593
	21st to end	Night	16% 7% 44% 30% 4	600
May	1st to 10th	Night	13% 7% 47% 29% 5%	600
	11th to 20th	Night	10% 7% 36% 42% 5%	591
	21st to end	Night	6% 3 32% 48% 11%	650
June	1st to 10th	Night	4 2 13% 56% 25% 1	600
	11th to 20th	Night	4 2 18% 56% 20% 1	600
	21st to end	Night	6% 2 14% 46% 32% 2	600
July	1st to 10th	Night	9% 1 10% 50% 26% 3	585
	11th to 20th	Night	5% 2 7% 51% 34% 2	582
	21st to end	Night	4 1 7% 53% 34% 2	657
August	1st to 10th	Night	1 5% 53% 38% 2	597
	11th to 20th	Night	2 1 7% 47% 39% 4	594
	21st to end	Night	4 1 5% 33% 49% 7%	660
September	1st to 10th	Night	7% 1 5% 32% 48% 8%	600
	11th to 20th	Night	10% 1 6% 24% 51% 8%	600
	21st to end	Night	8% 1 6% 33% 46% 7%	600
October	1st to 10th	Night	5% 1 5% 34% 48% 7%	600
	11th to 20th	Night	10% 1 12% 40% 34% 2	650
	21st to end	Night	7% 4 21% 44% 23% 2	880
November	1st to 10th	Night	10% 3 18% 43% 24% 2	820
	11th to 20th	Night	17% 2 20% 39% 21% 1	840
	21st to end	Night	20% 4 24% 36% 15% 1	1000
December	1st to 10th	Night	21% 4 22% 37% 15% 2	1050
	11th to 20th	Night	20% 6% 24% 35% 14%	1050
	21st to end	Night	18% 6% 25% 38% 13%	1155

Page generated at 2026-01-29 00:21:46. Version ac07

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