The Saddle
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the The Saddle clear sky chart from 2005-11-06 to 2025-03-12.

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	12% 6% 2 6% 5% 5% 5% 4 6% 8% 40%	109392
	Night	12% 6% 2 5% 4 4 4 4 6% 8% 45%	109631
Transparency	Day	40% 4 11% 22% 17% 5%	113055
	Night	36% 4 11% 24% 19% 6%	114107
Seeing	Day	22% 16% 25% 21% 11% 5%	15690
	Night	19% 15% 24% 25% 15% 2	25871

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	12% 6% 2 5% 4 4 4 3 5% 6% 51%	4056
	11th to 20th	Day	9% 6% 2 5% 4 4 4 3 5% 5% 53%	4060
	21st to end	Day	12% 8% 3 7% 5% 4 3 3 4 5% 45%	4466
February	1st to 10th	Day	11% 7% 3 7% 5% 6% 5% 4 6% 6% 40%	1800
	11th to 20th	Day	15% 8% 3 6% 5% 4 5% 2 6% 7% 39%	1833
	21st to end	Day	16% 7% 2 6% 4 5% 5% 3 5% 7% 40%	1716
March	1st to 10th	Day	21% 8% 2 6% 3 4 4 4 5% 8% 36%	3545
	11th to 20th	Day	9% 6% 2 5% 4 4 4 4 5% 6% 51%	3491
	21st to end	Day	18% 8% 2 6% 5% 4 4 3 4 6% 40%	3815
April	1st to 10th	Day	8% 5% 2 6% 5% 5% 5% 5% 6% 9% 46%	2137
	11th to 20th	Day	13% 7% 2 6% 4 4 4 3 5% 9% 43%	2254
	21st to end	Day	15% 7% 2 7% 5% 5% 4 4 5% 6% 40%	2420
May	1st to 10th	Day	14% 7% 3 8% 6% 6% 6% 4 8% 8% 31%	4082
	11th to 20th	Day	20% 8% 3 7% 5% 5% 5% 4 7% 7% 31%	4081
	21st to end	Day	10% 4 2 5% 5% 5% 6% 5% 7% 9% 41%	4476
June	1st to 10th	Day	11% 6% 2 6% 6% 6% 6% 6% 7% 10% 35%	2470
	11th to 20th	Day	9% 5% 2 6% 6% 6% 6% 5% 9% 11% 35%	2470
	21st to end	Day	9% 5% 2 7% 6% 6% 6% 5% 8% 9% 36%	2470
July	1st to 10th	Day	6% 4 2 7% 7% 7% 7% 7% 10% 9% 34%	4120
	11th to 20th	Day	8% 6% 3 7% 7% 7% 7% 5% 8% 11% 32%	4120
	21st to end	Day	12% 9% 4 11% 8% 8% 8% 6% 7% 8% 21%	4466
August	1st to 10th	Day	14% 6% 3 7% 5% 6% 7% 5% 8% 12% 26%	4104
	11th to 20th	Day	8% 5% 2 7% 5% 6% 8% 7% 8% 11% 32%	4044
	21st to end	Day	8% 5% 2 5% 5% 4 5% 5% 6% 12% 44%	4226
September	1st to 10th	Day	13% 5% 2 6% 5% 4 3 4 7% 7% 43%	2210
	11th to 20th	Day	17% 7% 2 7% 5% 4 5% 5% 5% 8% 35%	2090
	21st to end	Day	23% 8% 3 6% 5% 4 4 3 5% 7% 34%	2090
October	1st to 10th	Day	16% 5% 2 5% 4 3 4 3 4 5% 49%	1929
	11th to 20th	Day	13% 5% 2 4 2 3 4 3 5% 6% 52%	1900
	21st to end	Day	13% 4 2 6% 4 3 3 3 4 7% 52%	2090
November	1st to 10th	Day	11% 6% 2 5% 3 3 3 3 5% 6% 52%	1957
	11th to 20th	Day	13% 6% 1 4 3 4 4 4 5% 7% 49%	1835
	21st to end	Day	11% 6% 2 6% 4 3 5% 4 6% 7% 48%	1800
December	1st to 10th	Day	7% 5% 2 6% 5% 4 5% 4 6% 6% 50%	2930
	11th to 20th	Day	14% 5% 2 5% 4 4 5% 4 6% 8% 44%	3373
	21st to end	Day	15% 8% 2 6% 5% 5% 5% 5% 6% 7% 35%	4466
January	1st to 10th	Night	11% 6% 2 4 3 3 4 3 5% 7% 54%	5889
	11th to 20th	Night	10% 6% 2 5% 3 3 4 3 5% 6% 53%	5900
	21st to end	Night	15% 6% 2 5% 3 3 3 3 5% 6% 49%	6490
February	1st to 10th	Night	13% 7% 2 5% 4 4 4 4 6% 8% 43%	2600
	11th to 20th	Night	15% 8% 3 7% 5% 4 3 4 5% 6% 40%	2450
	21st to end	Night	12% 6% 3 6% 5% 4 4 4 6% 8% 42%	1912
March	1st to 10th	Night	22% 8% 2 5% 4 4 5% 4 5% 5% 35%	3528
	11th to 20th	Night	9% 4 1 4 3 4 4 4 5% 8% 54%	3498
	21st to end	Night	16% 6% 2 5% 4 4 4 4 5% 7% 45%	3817
April	1st to 10th	Night	10% 7% 2 6% 5% 4 3 4 5% 8% 45%	2042
	11th to 20th	Night	13% 6% 2 5% 4 3 4 4 4 8% 48%	1875
	21st to end	Night	15% 4 1 5% 4 3 3 5% 6% 6% 48%	1776
May	1st to 10th	Night	14% 7% 3 7% 4 4 4 4 7% 8% 38%	2813
	11th to 20th	Night	19% 8% 3 6% 4 4 3 3 5% 7% 37%	2812
	21st to end	Night	10% 4 2 4 4 4 4 4 7% 11% 47%	3079
June	1st to 10th	Night	10% 5% 2 5% 5% 6% 5% 5% 8% 11% 40%	1710
	11th to 20th	Night	10% 7% 2 5% 3 3 4 4 8% 9% 45%	1710
	21st to end	Night	7% 5% 1 5% 5% 5% 5% 4 8% 11% 45%	1710
July	1st to 10th	Night	5% 4 2 6% 6% 5% 6% 5% 9% 11% 40%	2840
	11th to 20th	Night	7% 5% 2 5% 5% 5% 5% 5% 9% 11% 42%	2840
	21st to end	Night	8% 7% 3 8% 6% 6% 7% 6% 9% 11% 30%	3087
August	1st to 10th	Night	17% 7% 2 7% 4 4 5% 5% 8% 11% 31%	2825
	11th to 20th	Night	8% 3 1 5% 5% 4 6% 5% 8% 11% 42%	2785
	21st to end	Night	6% 3 1 5% 4 5% 4 3 6% 9% 53%	3396
September	1st to 10th	Night	11% 6% 2 6% 4 4 4 4 6% 7% 47%	1966
	11th to 20th	Night	16% 8% 2 5% 3 4 4 4 5% 6% 42%	2090
	21st to end	Night	19% 8% 2 7% 4 4 4 3 4 6% 38%	2090
October	1st to 10th	Night	15% 7% 2 5% 4 3 4 2 5% 6% 48%	2249
	11th to 20th	Night	13% 5% 2 4 3 3 4 3 4 7% 52%	2280
	21st to end	Night	13% 4 2 4 3 3 3 3 4 5% 56%	2508
November	1st to 10th	Night	14% 6% 2 5% 3 3 3 3 5% 5% 50%	2341
	11th to 20th	Night	12% 5% 1 4 4 3 4 3 5% 7% 51%	2561
	21st to end	Night	12% 4 2 4 4 4 4 4 6% 7% 49%	2600
December	1st to 10th	Night	9% 5% 2 5% 4 3 4 4 5% 7% 54%	4250
	11th to 20th	Night	13% 9% 3 7% 4 4 5% 4 6% 7% 39%	4822
	21st to end	Night	15% 6% 2 5% 4 4 5% 4 6% 8% 41%	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	34% 2 5% 20% 31% 8%	4057
	11th to 20th	Day	33% 2 4 19% 31% 10%	4060
	21st to end	Day	42% 2 5% 22% 24% 5%	4466
February	1st to 10th	Day	42% 3 11% 22% 19% 4	1800
	11th to 20th	Day	44% 3 7% 23% 18% 5%	1842
	21st to end	Day	45% 2 10% 17% 19% 7%	1716
March	1st to 10th	Day	48% 1 7% 22% 14% 9%	3545
	11th to 20th	Day	34% 2 8% 26% 19% 10%	3491
	21st to end	Day	47% 3 8% 23% 15% 4	3815
April	1st to 10th	Day	33% 4 12% 24% 20% 7%	2137
	11th to 20th	Day	39% 3 12% 22% 19% 5%	2254
	21st to end	Day	45% 3 11% 24% 13% 3	2420
May	1st to 10th	Day	50% 3 14% 20% 11% 2	4120
	11th to 20th	Day	52% 3 10% 24% 9% 1	4085
	21st to end	Day	38% 3 17% 22% 17% 3	4489
June	1st to 10th	Day	41% 6% 16% 25% 11% 1	2470
	11th to 20th	Day	39% 7% 17% 21% 14% 2	2470
	21st to end	Day	41% 6% 15% 24% 12% 2	2470
July	1st to 10th	Day	38% 12% 19% 19% 8% 4	4055
	11th to 20th	Day	42% 8% 20% 23% 7% 1	4051
	21st to end	Day	56% 8% 12% 18% 6%	4324
August	1st to 10th	Day	46% 8% 18% 23% 5%	4091
	11th to 20th	Day	39% 8% 18% 24% 9% 2	4083
	21st to end	Day	33% 6% 17% 30% 12% 2	4226
September	1st to 10th	Day	39% 5% 12% 22% 18% 4	2210
	11th to 20th	Day	46% 4 8% 24% 16% 2	2090
	21st to end	Day	50% 3 8% 19% 17% 2	2090
October	1st to 10th	Day	31% 5% 7% 19% 29% 10%	3202
	11th to 20th	Day	23% 2 5% 26% 26% 18%	3140
	21st to end	Day	24% 3 9% 27% 22% 16%	3428
November	1st to 10th	Day	32% 3 9% 23% 27% 6%	1957
	11th to 20th	Day	35% 2 7% 23% 26% 8%	1835
	21st to end	Day	34% 3 8% 24% 26% 4	1800
December	1st to 10th	Day	33% 4 8% 22% 27% 6%	2930
	11th to 20th	Day	38% 3 12% 19% 22% 6%	3370
	21st to end	Day	46% 4 9% 23% 16% 3	4466
January	1st to 10th	Night	30% 1 6% 20% 30% 12%	5889
	11th to 20th	Night	33% 2 6% 19% 31% 9%	5900
	21st to end	Night	37% 2 6% 24% 26% 6%	6490
February	1st to 10th	Night	39% 3 10% 25% 20% 3	2600
	11th to 20th	Night	45% 2 8% 20% 18% 7%	2452
	21st to end	Night	40% 3 9% 24% 17% 7%	1912
March	1st to 10th	Night	50% 3 5% 21% 16% 5%	3528
	11th to 20th	Night	30% 2 8% 25% 21% 14%	3498
	21st to end	Night	40% 3 9% 24% 18% 6%	3817
April	1st to 10th	Night	38% 3 11% 21% 22% 4	2042
	11th to 20th	Night	36% 3 11% 22% 22% 6%	1875
	21st to end	Night	35% 3 13% 30% 16% 3	1776
May	1st to 10th	Night	44% 5% 16% 25% 10% 1	2840
	11th to 20th	Night	48% 3 11% 27% 10% 1	2813
	21st to end	Night	32% 3 21% 28% 12% 4	3087
June	1st to 10th	Night	36% 7% 17% 27% 12% 1	1710
	11th to 20th	Night	34% 6% 20% 26% 13% 2	1710
	21st to end	Night	32% 8% 18% 26% 14% 3	1710
July	1st to 10th	Night	35% 10% 21% 22% 10% 3	2795
	11th to 20th	Night	33% 8% 24% 26% 7% 1	2786
	21st to end	Night	44% 9% 19% 22% 6%	2988
August	1st to 10th	Night	45% 6% 21% 21% 6% 1	2814
	11th to 20th	Night	31% 7% 20% 30% 11% 1	2812
	21st to end	Night	28% 5% 16% 39% 10% 2	3396
September	1st to 10th	Night	37% 6% 14% 21% 16% 6%	1966
	11th to 20th	Night	43% 4 9% 23% 19% 2	2090
	21st to end	Night	49% 4 7% 21% 16% 3	2090
October	1st to 10th	Night	35% 3 7% 21% 26% 7%	3756
	11th to 20th	Night	24% 2 7% 24% 26% 17%	3779
	21st to end	Night	21% 2 6% 32% 23% 17%	4120
November	1st to 10th	Night	36% 2 9% 22% 24% 7%	2341
	11th to 20th	Night	33% 2 8% 22% 26% 10%	2561
	21st to end	Night	33% 3 8% 26% 25% 6%	2600
December	1st to 10th	Night	30% 4 8% 29% 27% 3	4250
	11th to 20th	Night	44% 3 9% 18% 17% 9%	4824
	21st to end	Night	40% 3 11% 24% 20% 2	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	37% 29% 25% 8% 2	300
	11th to 20th	Day	42% 28% 22% 7% 1	300
	21st to end	Day	34% 33% 28% 3 2	330
February	1st to 10th	Day	29% 33% 27% 10% 1	300
	11th to 20th	Day	50% 25% 21% 3 1	300
	21st to end	Day	37% 28% 25% 9% 1	315
March	1st to 10th	Day	30% 27% 27% 12% 4	500
	11th to 20th	Day	27% 28% 30% 11% 3 1	464
	21st to end	Day	28% 25% 31% 11% 4	506
April	1st to 10th	Day	25% 28% 27% 13% 7%	460
	11th to 20th	Day	25% 17% 27% 20% 7% 3	452
	21st to end	Day	25% 16% 33% 16% 7% 2	460
May	1st to 10th	Day	25% 18% 31% 16% 6% 4	463
	11th to 20th	Day	22% 12% 28% 21% 12% 5%	487
	21st to end	Day	18% 9% 25% 25% 17% 6%	529
June	1st to 10th	Day	13% 10% 30% 28% 13% 6%	490
	11th to 20th	Day	11% 10% 22% 31% 17% 8%	490
	21st to end	Day	10% 9% 28% 32% 15% 5%	490
July	1st to 10th	Day	12% 5% 17% 33% 24% 10%	485
	11th to 20th	Day	8% 3 17% 39% 24% 9%	484
	21st to end	Day	13% 5% 22% 28% 22% 10%	532
August	1st to 10th	Day	14% 8% 24% 23% 18% 13%	486
	11th to 20th	Day	11% 6% 20% 28% 22% 12%	479
	21st to end	Day	13% 4 14% 31% 23% 14%	539
September	1st to 10th	Day	15% 4 22% 25% 22% 12%	490
	11th to 20th	Day	18% 7% 16% 29% 22% 9%	490
	21st to end	Day	25% 12% 21% 26% 12% 4	490
October	1st to 10th	Day	22% 9% 23% 27% 14% 5%	490
	11th to 20th	Day	17% 20% 23% 22% 14% 3	490
	21st to end	Day	19% 18% 31% 22% 8% 3	539
November	1st to 10th	Day	22% 17% 28% 21% 10% 2	495
	11th to 20th	Day	26% 25% 26% 17% 5% 1	335
	21st to end	Day	28% 25% 29% 15% 3 1	300
December	1st to 10th	Day	27% 32% 32% 8% 1	300
	11th to 20th	Day	27% 26% 31% 14% 2	300
	21st to end	Day	32% 21% 30% 13% 4	330
January	1st to 10th	Night	25% 31% 26% 15% 3	800
	11th to 20th	Night	26% 26% 30% 16% 2	800
	21st to end	Night	22% 25% 34% 17% 1	880
February	1st to 10th	Night	23% 24% 30% 20% 2	800
	11th to 20th	Night	30% 31% 26% 12% 1	783
	21st to end	Night	25% 25% 32% 17% 2	660
March	1st to 10th	Night	21% 25% 31% 19% 4	800
	11th to 20th	Night	25% 22% 29% 18% 6% 1	767
	21st to end	Night	24% 20% 31% 19% 6%	836
April	1st to 10th	Night	24% 20% 29% 21% 6%	760
	11th to 20th	Night	21% 16% 32% 20% 9% 1	751
	21st to end	Night	19% 15% 32% 26% 8% 1	636
May	1st to 10th	Night	18% 13% 31% 25% 13% 1	570
	11th to 20th	Night	18% 9% 25% 27% 19% 2	561
	21st to end	Night	18% 5% 18% 29% 24% 7%	617
June	1st to 10th	Night	13% 3 21% 35% 25% 2	570
	11th to 20th	Night	14% 4 17% 29% 30% 6%	570
	21st to end	Night	9% 4 17% 38% 27% 5%	570
July	1st to 10th	Night	11% 3 11% 38% 33% 6%	555
	11th to 20th	Night	6% 2 11% 36% 38% 7%	552
	21st to end	Night	8% 3 13% 38% 32% 6%	624
August	1st to 10th	Night	16% 3 11% 34% 30% 4	567
	11th to 20th	Night	13% 3 11% 33% 34% 6%	564
	21st to end	Night	10% 3 13% 27% 37% 9%	782
September	1st to 10th	Night	14% 4 11% 32% 30% 8%	760
	11th to 20th	Night	20% 5% 12% 28% 29% 6%	760
	21st to end	Night	25% 8% 19% 25% 21% 2	760
October	1st to 10th	Night	19% 10% 20% 22% 23% 6%	760
	11th to 20th	Night	20% 13% 25% 25% 15% 2	760
	21st to end	Night	17% 14% 27% 28% 12% 2	836
November	1st to 10th	Night	21% 13% 26% 26% 13% 3	780
	11th to 20th	Night	19% 19% 27% 26% 8% 1	800
	21st to end	Night	19% 23% 26% 21% 10% 1	800
December	1st to 10th	Night	22% 26% 25% 22% 6%	800
	11th to 20th	Night	19% 25% 28% 22% 5% 1	800
	21st to end	Night	25% 23% 23% 24% 6%	880

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