Amarillo
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Amarillo clear sky chart from 2005-11-06 to 2026-03-18.

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	5% 4 2 4 3 3 3 3 5% 7% 61%	141005
	Night	4 4 1 4 3 3 4 3 5% 7% 60%	137906
Transparency	Day	23% 4 8% 22% 28% 15%	136073
	Night	22% 4 8% 21% 28% 17%	133848
Seeing	Day	7% 7% 29% 34% 19% 4	17057
	Night	7% 8% 37% 37% 11%	27165

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	5% 9% 4 6% 4 3 4 3 4 5% 54%	5287
	11th to 20th	Day	2 4 1 3 2 2 2 2 3 5% 73%	5347
	21st to end	Day	8% 4 1 5% 4 3 3 3 4 6% 58%	6468
February	1st to 10th	Day	5% 6% 1 4 3 3 3 3 5% 7% 61%	2100
	11th to 20th	Day	5% 7% 2 5% 3 3 3 3 4 6% 58%	2049
	21st to end	Day	4 4 1 4 3 2 4 3 5% 6% 65%	1730
March	1st to 10th	Day	6% 5% 1 4 3 3 3 3 4 6% 63%	4600
	11th to 20th	Day	6% 5% 2 4 3 3 3 3 4 7% 61%	4832
	21st to end	Day	4 5% 1 5% 3 4 4 4 5% 7% 59%	5734
April	1st to 10th	Day	6% 4 1 3 2 3 3 3 5% 5% 66%	2400
	11th to 20th	Day	7% 4 2 4 3 3 3 3 6% 6% 60%	2371
	21st to end	Day	5% 3 1 4 3 3 3 4 5% 6% 62%	2410
May	1st to 10th	Day	10% 5% 2 4 3 3 3 3 5% 7% 56%	5900
	11th to 20th	Day	6% 4 1 4 2 3 2 2 4 6% 66%	5862
	21st to end	Day	7% 5% 2 4 3 2 3 3 5% 7% 60%	6446
June	1st to 10th	Day	5% 4 1 5% 4 4 4 4 6% 10% 53%	2600
	11th to 20th	Day	3 3 1 3 3 3 3 4 5% 7% 64%	2698
	21st to end	Day	3 3 1 4 3 4 5% 5% 6% 9% 57%	2800
July	1st to 10th	Day	7% 5% 2 6% 4 4 5% 4 6% 7% 50%	6339
	11th to 20th	Day	3 2 1 4 3 4 4 4 6% 10% 60%	5999
	21st to end	Day	2 3 1 4 4 3 4 4 6% 10% 60%	6424
August	1st to 10th	Day	2 3 1 4 3 4 4 4 6% 9% 60%	5398
	11th to 20th	Day	3 2 1 4 4 4 5% 4 6% 10% 57%	5366
	21st to end	Day	7% 4 2 5% 4 4 5% 3 6% 9% 52%	5984
September	1st to 10th	Day	6% 4 2 5% 3 4 4 3 4 7% 56%	2386
	11th to 20th	Day	6% 4 2 5% 4 4 4 3 5% 7% 57%	2200
	21st to end	Day	5% 2 1 3 2 2 3 3 4 7% 66%	2200
October	1st to 10th	Day	5% 2 1 2 2 2 2 2 3 4 76%	3590
	11th to 20th	Day	6% 5% 2 5% 3 2 2 3 4 5% 64%	3517
	21st to end	Day	4 3 1 2 2 2 3 2 3 4 75%	3237
November	1st to 10th	Day	4 2 1 4 2 2 2 2 4 6% 68%	1853
	11th to 20th	Day	2 3 2 3 3 3 3 3 4 5% 71%	1890
	21st to end	Day	8% 5% 2 4 3 3 3 2 4 5% 63%	1890
December	1st to 10th	Day	3 3 1 3 2 3 2 3 4 6% 69%	3030
	11th to 20th	Day	3 4 1 4 3 3 4 3 5% 6% 64%	3481
	21st to end	Day	4 5% 2 6% 3 3 3 3 4 5% 62%	4587
January	1st to 10th	Night	4 7% 3 6% 4 4 4 4 5% 6% 53%	7634
	11th to 20th	Night	2 3 1 3 2 2 2 2 4 5% 73%	7680
	21st to end	Night	6% 5% 2 6% 4 4 4 3 5% 7% 55%	7764
February	1st to 10th	Night	5% 5% 2 4 4 3 4 2 3 6% 62%	2520
	11th to 20th	Night	5% 6% 2 6% 4 3 3 3 4 7% 57%	2458
	21st to end	Night	5% 3 2 3 2 3 3 4 6% 7% 63%	2076
March	1st to 10th	Night	4 5% 2 3 3 3 3 2 4 6% 66%	5494
	11th to 20th	Night	5% 3 1 5% 3 3 3 3 5% 6% 64%	5277
	21st to end	Night	3 3 1 5% 4 3 4 3 5% 8% 60%	5204
April	1st to 10th	Night	5% 4 1 3 3 2 2 3 5% 7% 64%	2000
	11th to 20th	Night	7% 4 1 4 3 3 3 4 6% 5% 60%	1977
	21st to end	Night	7% 4 1 3 3 2 3 3 5% 8% 60%	1990
May	1st to 10th	Night	8% 5% 1 4 3 3 3 3 4 6% 57%	4080
	11th to 20th	Night	5% 4 1 3 3 3 4 3 5% 7% 62%	4053
	21st to end	Night	7% 6% 2 4 3 3 2 3 5% 6% 58%	4451
June	1st to 10th	Night	4 3 2 3 4 4 4 5% 8% 12% 52%	1800
	11th to 20th	Night	3 2 1 3 3 3 5% 3 6% 8% 64%	1693
	21st to end	Night	3 3 1 3 2 5% 4 4 7% 10% 58%	1600
July	1st to 10th	Night	7% 5% 2 8% 5% 4 5% 4 6% 8% 46%	3640
	11th to 20th	Night	3 3 2 6% 4 4 6% 5% 7% 12% 49%	3948
	21st to end	Night	3 2 1 5% 4 4 5% 4 8% 12% 51%	4449
August	1st to 10th	Night	3 3 1 4 4 4 5% 5% 7% 12% 52%	4409
	11th to 20th	Night	3 3 2 5% 4 5% 6% 6% 8% 12% 47%	4483
	21st to end	Night	7% 5% 2 5% 3 4 5% 5% 8% 10% 47%	4993
September	1st to 10th	Night	5% 4 1 4 4 3 3 4 5% 8% 59%	2012
	11th to 20th	Night	6% 5% 2 5% 4 3 3 4 6% 7% 56%	2200
	21st to end	Night	6% 2 1 2 2 3 3 3 4 8% 66%	2200
October	1st to 10th	Night	4 2 1 3 1 2 2 1 2 4 76%	3590
	11th to 20th	Night	7% 4 1 5% 2 2 3 2 3 5% 66%	3619
	21st to end	Night	4 3 1 3 2 2 2 2 4 5% 72%	4528
November	1st to 10th	Night	5% 3 1 2 2 2 2 2 4 6% 71%	2665
	11th to 20th	Night	2 3 1 3 2 3 3 3 4 6% 70%	2730
	21st to end	Night	5% 5% 1 4 3 3 2 3 4 6% 64%	2730
December	1st to 10th	Night	3 3 1 3 2 2 2 2 5% 7% 69%	4380
	11th to 20th	Night	3 3 1 3 3 3 3 2 5% 8% 67%	4946
	21st to end	Night	4 4 2 5% 3 3 3 3 4 7% 61%	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	33% 3 4 22% 28% 10%	5290
	11th to 20th	Day	17% 2 7% 17% 38% 19%	5347
	21st to end	Day	28% 3 5% 17% 35% 13%	6468
February	1st to 10th	Day	24% 3 8% 22% 28% 15%	2100
	11th to 20th	Day	28% 3 6% 23% 26% 14%	2059
	21st to end	Day	21% 2 4 19% 33% 21%	1730
March	1st to 10th	Day	22% 3 4 11% 28% 32%	4600
	11th to 20th	Day	24% 3 5% 17% 31% 20%	4832
	21st to end	Day	23% 5% 6% 27% 29% 10%	5734
April	1st to 10th	Day	21% 4 6% 16% 30% 23%	2400
	11th to 20th	Day	25% 3 6% 19% 26% 21%	2374
	21st to end	Day	21% 4 10% 24% 27% 13%	2410
May	1st to 10th	Day	27% 5% 10% 22% 19% 17%	5900
	11th to 20th	Day	21% 3 6% 15% 25% 29%	5866
	21st to end	Day	25% 5% 9% 18% 19% 24%	6447
June	1st to 10th	Day	26% 6% 15% 28% 16% 10%	2600
	11th to 20th	Day	18% 5% 9% 23% 26% 19%	2698
	21st to end	Day	21% 6% 12% 26% 22% 13%	2800
July	1st to 10th	Day	30% 8% 10% 21% 26% 4	6271
	11th to 20th	Day	18% 6% 13% 34% 24% 5%	5927
	21st to end	Day	18% 7% 16% 34% 20% 4	6240
August	1st to 10th	Day	18% 7% 13% 29% 21% 11%	3928
	11th to 20th	Day	18% 6% 10% 22% 32% 12%	3882
	21st to end	Day	23% 6% 11% 28% 26% 5%	4311
September	1st to 10th	Day	26% 6% 11% 22% 23% 11%	2386
	11th to 20th	Day	27% 5% 9% 21% 30% 8%	2200
	21st to end	Day	19% 4 7% 24% 32% 15%	2200
October	1st to 10th	Day	15% 3 5% 13% 39% 25%	3590
	11th to 20th	Day	23% 4 9% 18% 28% 19%	3517
	21st to end	Day	15% 2 3 22% 37% 21%	3237
November	1st to 10th	Day	18% 2 6% 18% 36% 19%	1853
	11th to 20th	Day	16% 3 6% 24% 34% 17%	1890
	21st to end	Day	25% 2 4 18% 32% 19%	1890
December	1st to 10th	Day	16% 3 7% 31% 31% 12%	3030
	11th to 20th	Day	22% 3 5% 17% 38% 16%	3479
	21st to end	Day	25% 3 6% 25% 28% 15%	4587
January	1st to 10th	Night	30% 3 5% 27% 29% 6%	7635
	11th to 20th	Night	14% 2 9% 20% 36% 19%	7680
	21st to end	Night	29% 4 8% 17% 29% 13%	7764
February	1st to 10th	Night	24% 3 6% 20% 29% 18%	2520
	11th to 20th	Night	28% 3 8% 20% 24% 17%	2458
	21st to end	Night	20% 3 4 18% 30% 24%	2076
March	1st to 10th	Night	20% 3 4 13% 25% 35%	5494
	11th to 20th	Night	21% 4 5% 18% 21% 32%	5277
	21st to end	Night	21% 4 7% 22% 30% 15%	5204
April	1st to 10th	Night	20% 3 7% 20% 27% 23%	2000
	11th to 20th	Night	23% 5% 9% 21% 23% 19%	1977
	21st to end	Night	22% 5% 11% 25% 23% 14%	1990
May	1st to 10th	Night	27% 5% 10% 19% 20% 18%	4080
	11th to 20th	Night	22% 5% 8% 12% 23% 29%	4054
	21st to end	Night	27% 6% 10% 15% 14% 29%	4452
June	1st to 10th	Night	22% 8% 19% 27% 15% 9%	1800
	11th to 20th	Night	17% 6% 13% 22% 24% 18%	1693
	21st to end	Night	20% 7% 14% 28% 20% 12%	1600
July	1st to 10th	Night	34% 9% 12% 27% 16% 2	3600
	11th to 20th	Night	24% 7% 15% 26% 23% 5%	3897
	21st to end	Night	22% 8% 13% 35% 19% 3	4320
August	1st to 10th	Night	22% 8% 14% 24% 21% 11%	3203
	11th to 20th	Night	23% 7% 13% 23% 26% 8%	3243
	21st to end	Night	23% 7% 15% 27% 22% 6%	3597
September	1st to 10th	Night	24% 6% 12% 24% 22% 12%	2012
	11th to 20th	Night	27% 6% 10% 25% 23% 9%	2200
	21st to end	Night	18% 4 8% 22% 32% 16%	2200
October	1st to 10th	Night	15% 3 6% 11% 35% 31%	3590
	11th to 20th	Night	22% 4 7% 16% 29% 21%	3619
	21st to end	Night	16% 2 4 18% 42% 17%	4528
November	1st to 10th	Night	16% 2 7% 19% 34% 22%	2665
	11th to 20th	Night	16% 3 4 23% 36% 18%	2730
	21st to end	Night	22% 3 4 19% 33% 19%	2730
December	1st to 10th	Night	16% 3 7% 30% 35% 9%	4380
	11th to 20th	Night	18% 2 4 18% 40% 19%	4947
	21st to end	Night	23% 4 7% 20% 33% 13%	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	7% 11% 44% 27% 9% 1	330
	11th to 20th	Day	9% 16% 36% 25% 14% 1	330
	21st to end	Day	7% 11% 39% 31% 12% 1	363
February	1st to 10th	Day	8% 12% 38% 31% 11% 1	330
	11th to 20th	Day	11% 16% 40% 22% 8% 2	330
	21st to end	Day	7% 14% 45% 27% 6%	273
March	1st to 10th	Day	8% 10% 43% 31% 8%	330
	11th to 20th	Day	15% 13% 36% 24% 10% 2	321
	21st to end	Day	10% 13% 43% 25% 9% 1	445
April	1st to 10th	Day	11% 15% 44% 23% 7% 1	500
	11th to 20th	Day	9% 17% 42% 26% 5%	492
	21st to end	Day	9% 15% 39% 27% 10% 1	510
May	1st to 10th	Day	8% 10% 37% 33% 12% 1	703
	11th to 20th	Day	9% 9% 31% 31% 17% 3	725
	21st to end	Day	7% 9% 36% 33% 14% 2	789
June	1st to 10th	Day	6% 4 27% 39% 20% 4	730
	11th to 20th	Day	3 4 32% 39% 19% 3	730
	21st to end	Day	4 3 23% 43% 22% 4	730
July	1st to 10th	Day	7% 2 13% 36% 31% 11%	721
	11th to 20th	Day	3 1 9% 41% 36% 10%	718
	21st to end	Day	2 1 9% 38% 40% 11%	794
August	1st to 10th	Day	3 1 13% 40% 34% 9%	551
	11th to 20th	Day	5% 2 11% 40% 31% 11%	517
	21st to end	Day	6% 2 11% 41% 31% 9%	583
September	1st to 10th	Day	5% 1 15% 39% 32% 8%	516
	11th to 20th	Day	2 2 18% 43% 27% 8%	330
	21st to end	Day	6% 4 22% 33% 29% 6%	330
October	1st to 10th	Day	9% 3 29% 32% 23% 4	330
	11th to 20th	Day	6% 7% 30% 38% 14% 4	330
	21st to end	Day	13% 10% 29% 28% 16% 4	363
November	1st to 10th	Day	9% 8% 31% 34% 15% 3	330
	11th to 20th	Day	4 11% 33% 34% 15% 3	330
	21st to end	Day	13% 12% 35% 26% 11% 3	330
December	1st to 10th	Day	5% 10% 41% 31% 11% 2	330
	11th to 20th	Day	7% 8% 33% 40% 10% 1	330
	21st to end	Day	9% 13% 42% 24% 10% 1	363
January	1st to 10th	Night	5% 12% 39% 36% 7%	1050
	11th to 20th	Night	7% 9% 42% 32% 10% 1	1050
	21st to end	Night	6% 7% 43% 35% 8%	929
February	1st to 10th	Night	7% 10% 45% 32% 5%	840
	11th to 20th	Night	9% 13% 46% 27% 4	824
	21st to end	Night	7% 13% 49% 28% 3	692
March	1st to 10th	Night	8% 14% 47% 28% 3	840
	11th to 20th	Night	9% 15% 41% 30% 5%	724
	21st to end	Night	6% 16% 55% 21% 3	660
April	1st to 10th	Night	7% 12% 51% 27% 3	600
	11th to 20th	Night	8% 12% 56% 22% 2	593
	21st to end	Night	9% 12% 49% 26% 4	600
May	1st to 10th	Night	7% 11% 47% 31% 5%	600
	11th to 20th	Night	9% 9% 39% 33% 9% 1	591
	21st to end	Night	7% 8% 49% 31% 6%	650
June	1st to 10th	Night	5% 5% 40% 42% 9%	600
	11th to 20th	Night	4 5% 47% 38% 6%	600
	21st to end	Night	3 3 36% 46% 13%	600
July	1st to 10th	Night	4 2 21% 51% 21% 1	585
	11th to 20th	Night	3 1 14% 57% 25%	582
	21st to end	Night	4 1 13% 56% 26% 1	657
August	1st to 10th	Night	3 1 17% 50% 28% 1	597
	11th to 20th	Night	5% 3 16% 54% 21% 1	594
	21st to end	Night	5% 2 14% 51% 27% 2	660
September	1st to 10th	Night	6% 2 16% 56% 20% 1	600
	11th to 20th	Night	8% 3 27% 48% 14%	600
	21st to end	Night	7% 4 26% 44% 19% 1	600
October	1st to 10th	Night	9% 4 34% 42% 11% 1	600
	11th to 20th	Night	8% 8% 39% 37% 7%	625
	21st to end	Night	8% 8% 33% 34% 16% 1	1042
November	1st to 10th	Night	7% 6% 36% 37% 13% 1	1025
	11th to 20th	Night	4 9% 39% 36% 12%	1050
	21st to end	Night	7% 10% 34% 37% 11%	1050
December	1st to 10th	Night	7% 9% 37% 38% 9%	1050
	11th to 20th	Night	7% 9% 42% 34% 7%	1050
	21st to end	Night	9% 11% 41% 33% 6%	1155

Page generated at 2026-03-15 01:23:53. Version ac07

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