Laredo
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Laredo clear sky chart from 2005-11-06 to 2025-01-07.

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% 4 4 4 3 5% 7% 51%	104945
	Night	11% 5% 2 4 3 3 3 3 5% 7% 54%	104239
Transparency	Day	18% 45% 7% 14% 10% 6%	108871
	Night	18% 45% 7% 13% 10% 7%	108440
Seeing	Day	9% 4 18% 35% 26% 8%	14642
	Night	12% 4 27% 44% 13% 1	24742

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	13% 5% 2 6% 4 3 3 3 3 5% 53%	2901
	11th to 20th	Day	12% 4 1 3 3 3 2 2 4 6% 58%	3116
	21st to end	Day	16% 7% 2 6% 4 4 3 4 6% 8% 40%	3487
February	1st to 10th	Day	12% 8% 3 7% 5% 4 3 3 4 5% 47%	1900
	11th to 20th	Day	15% 6% 2 5% 3 3 3 3 4 5% 52%	1849
	21st to end	Day	12% 6% 2 4 3 4 3 3 5% 6% 53%	1570
March	1st to 10th	Day	14% 6% 2 6% 4 4 5% 4 7% 8% 41%	3281
	11th to 20th	Day	23% 7% 3 5% 4 3 4 3 5% 5% 38%	3480
	21st to end	Day	8% 4 1 3 2 3 3 3 5% 7% 60%	3814
April	1st to 10th	Day	12% 5% 2 5% 4 4 4 3 5% 6% 51%	2090
	11th to 20th	Day	10% 7% 2 6% 4 3 4 4 5% 8% 48%	2154
	21st to end	Day	10% 7% 2 5% 4 4 4 4 5% 7% 49%	2280
May	1st to 10th	Day	12% 6% 2 6% 4 4 3 4 6% 9% 45%	4010
	11th to 20th	Day	9% 6% 2 7% 4 4 4 4 5% 7% 48%	4082
	21st to end	Day	5% 4 2 5% 4 4 4 4 5% 9% 55%	4477
June	1st to 10th	Day	2 2 1 4 3 4 4 4 7% 10% 58%	2470
	11th to 20th	Day	3 3 1 3 3 4 3 3 5% 9% 62%	2470
	21st to end	Day	5% 4 1 4 5% 5% 5% 5% 6% 10% 49%	2470
July	1st to 10th	Day	5% 4 1 5% 4 4 4 3 6% 10% 54%	4120
	11th to 20th	Day	6% 6% 2 7% 5% 5% 6% 5% 6% 9% 43%	4120
	21st to end	Day	4 3 1 5% 4 4 5% 4 7% 10% 51%	4218
August	1st to 10th	Day	1 1 2 2 2 2 2 3 6% 80%	3785
	11th to 20th	Day	2 1 1 3 2 3 4 4 7% 10% 63%	3726
	21st to end	Day	4 3 1 4 3 4 4 4 6% 10% 57%	4094
September	1st to 10th	Day	9% 7% 2 8% 5% 6% 6% 4 5% 8% 41%	2090
	11th to 20th	Day	10% 5% 2 6% 5% 5% 5% 5% 7% 8% 42%	2090
	21st to end	Day	7% 5% 1 5% 5% 5% 4 4 7% 8% 50%	2090
October	1st to 10th	Day	6% 4 2 5% 4 4 4 4 5% 5% 58%	2090
	11th to 20th	Day	11% 5% 2 5% 3 4 4 3 4 7% 51%	2090
	21st to end	Day	10% 4 2 4 3 3 3 2 4 5% 61%	2109
November	1st to 10th	Day	11% 6% 3 6% 4 3 4 3 4 6% 50%	1958
	11th to 20th	Day	13% 6% 2 6% 3 3 2 3 3 4 53%	1845
	21st to end	Day	16% 7% 2 5% 4 4 3 3 4 5% 49%	1800
December	1st to 10th	Day	33% 7% 2 4 3 3 3 3 4 5% 34%	2940
	11th to 20th	Day	14% 8% 2 6% 4 4 4 4 4 6% 45%	3391
	21st to end	Day	10% 6% 2 5% 3 3 4 3 4 6% 55%	4488
January	1st to 10th	Night	15% 5% 2 3 2 2 3 3 4 6% 54%	4187
	11th to 20th	Night	12% 4 1 3 2 2 2 2 4 7% 61%	3882
	21st to end	Night	19% 6% 2 6% 4 3 4 3 4 7% 42%	4180
February	1st to 10th	Night	11% 7% 2 5% 3 3 4 3 5% 6% 52%	2280
	11th to 20th	Night	16% 6% 1 5% 2 3 3 2 4 6% 51%	2218
	21st to end	Night	11% 5% 2 4 2 3 3 3 4 6% 55%	1884
March	1st to 10th	Night	14% 6% 2 5% 4 4 4 4 6% 7% 45%	3575
	11th to 20th	Night	22% 8% 3 6% 4 4 4 3 4 5% 36%	3480
	21st to end	Night	10% 3 1 3 2 2 2 3 5% 6% 62%	3817
April	1st to 10th	Night	10% 4 2 4 3 4 4 3 6% 9% 51%	2090
	11th to 20th	Night	12% 5% 2 4 3 3 4 3 5% 7% 52%	1970
	21st to end	Night	12% 6% 2 5% 4 3 3 3 5% 8% 49%	1900
May	1st to 10th	Night	10% 5% 2 5% 3 4 4 3 6% 8% 50%	2891
	11th to 20th	Night	8% 6% 2 5% 4 3 4 3 6% 7% 52%	2823
	21st to end	Night	5% 5% 2 5% 4 3 4 3 6% 9% 53%	3090
June	1st to 10th	Night	2 2 1 3 3 3 3 3 6% 10% 65%	1710
	11th to 20th	Night	1 2 1 3 2 3 3 3 5% 9% 67%	1710
	21st to end	Night	3 3 1 4 4 4 5% 4 7% 11% 54%	1710
July	1st to 10th	Night	5% 4 2 4 3 3 4 3 6% 9% 58%	2850
	11th to 20th	Night	7% 5% 2 6% 5% 4 5% 4 8% 9% 46%	2850
	21st to end	Night	6% 4 1 5% 3 3 4 3 5% 9% 56%	3339
August	1st to 10th	Night	1 1 1 1 1 1 1 3 5% 84%	3155
	11th to 20th	Night	1 2 1 3 3 4 5% 4 7% 11% 58%	3113
	21st to end	Night	3 2 1 4 3 3 3 3 5% 11% 62%	3570
September	1st to 10th	Night	8% 7% 2 6% 4 4 5% 4 7% 9% 43%	2090
	11th to 20th	Night	8% 5% 2 5% 4 4 4 4 8% 9% 46%	2090
	21st to end	Night	8% 3 1 5% 3 3 3 4 6% 9% 56%	2090
October	1st to 10th	Night	5% 3 1 4 4 3 3 4 4 7% 62%	2090
	11th to 20th	Night	11% 4 2 4 3 3 3 3 4 6% 58%	2090
	21st to end	Night	9% 4 1 3 2 2 3 2 3 4 67%	2469
November	1st to 10th	Night	11% 5% 1 4 2 3 3 3 4 6% 58%	2340
	11th to 20th	Night	12% 5% 2 4 3 3 3 3 4 5% 55%	2550
	21st to end	Night	16% 6% 2 4 4 3 3 3 4 5% 52%	2600
December	1st to 10th	Night	35% 7% 2 4 3 2 3 2 4 4 34%	4250
	11th to 20th	Night	16% 6% 2 5% 3 3 3 3 4 6% 50%	4816
	21st to end	Night	9% 5% 2 4 3 3 3 3 4 6% 57%	6490

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	24% 36% 4 6% 20% 11%	2902
	11th to 20th	Day	15% 36% 3 15% 19% 12%	3116
	21st to end	Day	27% 40% 5% 9% 16% 3	3487
February	1st to 10th	Day	17% 65% 3 3 5% 7%	1900
	11th to 20th	Day	13% 64% 3 7% 8% 5%	1859
	21st to end	Day	15% 65% 4 6% 7% 4	1570
March	1st to 10th	Day	29% 42% 7% 11% 8% 2	3281
	11th to 20th	Day	37% 41% 4 6% 8% 5%	3480
	21st to end	Day	14% 41% 6% 14% 11% 14%	3814
April	1st to 10th	Day	12% 65% 4 6% 6% 7%	2090
	11th to 20th	Day	14% 66% 3 6% 6% 4	2154
	21st to end	Day	12% 65% 3 7% 7% 6%	2280
May	1st to 10th	Day	23% 42% 9% 14% 8% 5%	4047
	11th to 20th	Day	22% 42% 7% 12% 8% 9%	4086
	21st to end	Day	14% 41% 6% 31% 7% 1	4489
June	1st to 10th	Day	6% 66% 5% 13% 9% 1	2470
	11th to 20th	Day	11% 66% 3 8% 10% 2	2470
	21st to end	Day	12% 65% 6% 8% 8% 1	2470
July	1st to 10th	Day	11% 37% 12% 34% 6%	4056
	11th to 20th	Day	27% 39% 13% 14% 5% 2	4051
	21st to end	Day	18% 39% 14% 21% 7% 1	4085
August	1st to 10th	Day	4 37% 7% 31% 20% 1	3772
	11th to 20th	Day	10% 39% 16% 30% 6% 1	3762
	21st to end	Day	10% 39% 15% 22% 14% 1	4093
September	1st to 10th	Day	16% 61% 6% 7% 7% 3	2090
	11th to 20th	Day	14% 61% 5% 10% 7% 2	2090
	21st to end	Day	14% 62% 6% 11% 4 3	2090
October	1st to 10th	Day	10% 37% 3 6% 14% 30%	3480
	11th to 20th	Day	18% 38% 5% 9% 9% 20%	3458
	21st to end	Day	15% 37% 4 11% 26% 7%	3459
November	1st to 10th	Day	21% 57% 6% 7% 5% 4	1958
	11th to 20th	Day	20% 57% 3 9% 6% 5%	1845
	21st to end	Day	20% 57% 3 9% 7% 5%	1800
December	1st to 10th	Day	42% 36% 4 7% 8% 4	2940
	11th to 20th	Day	26% 33% 8% 16% 6% 11%	3389
	21st to end	Day	24% 27% 3 16% 18% 11%	4488
January	1st to 10th	Night	21% 36% 4 9% 15% 14%	4187
	11th to 20th	Night	15% 36% 2 12% 18% 17%	3882
	21st to end	Night	28% 40% 4 9% 14% 5%	4180
February	1st to 10th	Night	15% 65% 3 4 6% 8%	2280
	11th to 20th	Night	12% 64% 3 8% 8% 5%	2218
	21st to end	Night	13% 65% 5% 7% 6% 4	1884
March	1st to 10th	Night	30% 42% 7% 13% 5% 3	3575
	11th to 20th	Night	38% 42% 5% 6% 6% 3	3480
	21st to end	Night	13% 40% 5% 17% 15% 10%	3817
April	1st to 10th	Night	11% 65% 3 9% 6% 6%	2090
	11th to 20th	Night	13% 66% 5% 4 6% 4	1970
	21st to end	Night	12% 64% 4 7% 8% 3	1900
May	1st to 10th	Night	19% 42% 9% 15% 9% 5%	2919
	11th to 20th	Night	17% 41% 10% 12% 12% 8%	2824
	21st to end	Night	18% 41% 6% 28% 6%	3099
June	1st to 10th	Night	3 65% 7% 15% 10% 1	1710
	11th to 20th	Night	8% 66% 3 10% 11% 1	1710
	21st to end	Night	9% 65% 8% 11% 6% 1	1710
July	1st to 10th	Night	8% 38% 16% 34% 4	2805
	11th to 20th	Night	28% 38% 16% 12% 5% 1	2796
	21st to end	Night	19% 37% 16% 22% 6%	3233
August	1st to 10th	Night	3 36% 8% 31% 21%	3144
	11th to 20th	Night	12% 39% 21% 23% 5%	3143
	21st to end	Night	7% 38% 18% 25% 10% 1	3570
September	1st to 10th	Night	13% 63% 7% 8% 8% 3	2090
	11th to 20th	Night	12% 61% 7% 12% 6% 1	2090
	21st to end	Night	13% 61% 7% 14% 3 2	2090
October	1st to 10th	Night	11% 38% 4 9% 11% 27%	3480
	11th to 20th	Night	12% 38% 7% 10% 16% 18%	3460
	21st to end	Night	15% 37% 5% 11% 21% 10%	4057
November	1st to 10th	Night	18% 57% 6% 9% 6% 4	2340
	11th to 20th	Night	19% 57% 5% 8% 5% 6%	2550
	21st to end	Night	19% 57% 3 8% 10% 4	2600
December	1st to 10th	Night	44% 35% 4 5% 7% 5%	4250
	11th to 20th	Night	24% 33% 5% 17% 10% 11%	4817
	21st to end	Night	23% 28% 5% 14% 14% 16%	6490

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% 6% 22% 36% 14% 3	288
	11th to 20th	Day	16% 7% 21% 35% 18% 3	270
	21st to end	Day	21% 6% 30% 24% 17% 2	297
February	1st to 10th	Day	15% 9% 28% 26% 18% 4	270
	11th to 20th	Day	18% 9% 32% 27% 13% 2	270
	21st to end	Day	16% 8% 30% 37% 9%	225
March	1st to 10th	Day	19% 5% 33% 30% 13% 1	270
	11th to 20th	Day	14% 7% 33% 34% 10% 1	270
	21st to end	Day	10% 7% 38% 37% 8%	297
April	1st to 10th	Day	11% 9% 38% 33% 9%	270
	11th to 20th	Day	10% 9% 32% 33% 14% 1	352
	21st to end	Day	8% 7% 42% 33% 9% 1	460
May	1st to 10th	Day	9% 6% 34% 37% 12% 1	606
	11th to 20th	Day	12% 3 32% 40% 11% 2	675
	21st to end	Day	7% 3 26% 47% 15% 1	734
June	1st to 10th	Day	2 1 12% 50% 31% 4	680
	11th to 20th	Day	3 1 10% 55% 28% 3	680
	21st to end	Day	6% 1 10% 42% 32% 9%	680
July	1st to 10th	Day	6% 1 9% 37% 37% 9%	671
	11th to 20th	Day	3 1 5% 37% 47% 7%	668
	21st to end	Day	3 2 5% 41% 38% 11%	593
August	1st to 10th	Day	1 4 37% 44% 15%	487
	11th to 20th	Day	3 1 2 33% 45% 17%	477
	21st to end	Day	4 1 3 27% 34% 29%	492
September	1st to 10th	Day	10% 6% 19% 42% 23%	300
	11th to 20th	Day	4 1 6% 13% 36% 39%	300
	21st to end	Day	6% 5% 15% 45% 28%	300
October	1st to 10th	Day	9% 2 4 21% 40% 24%	300
	11th to 20th	Day	13% 1 7% 30% 33% 16%	300
	21st to end	Day	12% 6% 16% 29% 26% 10%	330
November	1st to 10th	Day	11% 4 15% 33% 27% 10%	300
	11th to 20th	Day	19% 4 15% 24% 31% 7%	300
	21st to end	Day	20% 6% 21% 26% 21% 5%	300
December	1st to 10th	Day	19% 4 22% 22% 25% 9%	300
	11th to 20th	Day	17% 9% 21% 26% 23% 4	300
	21st to end	Day	14% 5% 20% 32% 23% 5%	330
January	1st to 10th	Night	19% 4 23% 42% 12% 1	981
	11th to 20th	Night	20% 4 27% 42% 8%	803
	21st to end	Night	18% 7% 25% 42% 8%	836
February	1st to 10th	Night	14% 7% 33% 39% 6%	760
	11th to 20th	Night	21% 6% 35% 34% 5%	744
	21st to end	Night	15% 6% 42% 33% 4	628
March	1st to 10th	Night	14% 10% 40% 32% 4	666
	11th to 20th	Night	12% 9% 44% 31% 3	570
	21st to end	Night	10% 7% 54% 27% 2	627
April	1st to 10th	Night	10% 6% 50% 32% 2	570
	11th to 20th	Night	12% 7% 47% 32% 2	563
	21st to end	Night	10% 9% 51% 26% 3	570
May	1st to 10th	Night	9% 7% 50% 32% 2	570
	11th to 20th	Night	8% 5% 46% 37% 3	561
	21st to end	Night	6% 4 47% 38% 5%	617
June	1st to 10th	Night	2 1 30% 57% 9%	570
	11th to 20th	Night	3 1 35% 55% 6% 1	570
	21st to end	Night	4 1 25% 55% 15% 1	570
July	1st to 10th	Night	7% 1 15% 62% 13% 1	555
	11th to 20th	Night	3 1 12% 69% 15%	552
	21st to end	Night	4 1 13% 67% 14%	624
August	1st to 10th	Night	2 1 12% 67% 18% 1	567
	11th to 20th	Night	3 13% 66% 17% 1	564
	21st to end	Night	4 1 7% 59% 26% 3	627
September	1st to 10th	Night	9% 1 11% 48% 26% 4	570
	11th to 20th	Night	9% 1 7% 43% 35% 4	570
	21st to end	Night	8% 11% 45% 32% 4	570
October	1st to 10th	Night	5% 1 12% 50% 30% 1	570
	11th to 20th	Night	12% 1 16% 48% 22% 1	570
	21st to end	Night	10% 4 23% 42% 20% 1	797
November	1st to 10th	Night	11% 3 21% 42% 21% 1	780
	11th to 20th	Night	14% 3 18% 43% 20% 2	950
	21st to end	Night	17% 4 23% 38% 17% 1	1000
December	1st to 10th	Night	20% 3 20% 42% 15% 1	1000
	11th to 20th	Night	21% 5% 23% 40% 11% 1	1000
	21st to end	Night	15% 4 25% 41% 15%	1100

Page generated at 2025-01-04 02:24:00. Version ac07

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