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 2024-02-10.

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	14% 6% 3 5% 6% 4 5% 5% 6% 8% 39%	78689
	Night	13% 6% 2 5% 5% 3 4 5% 6% 7% 44%	80290
Transparency	Day	42% 4 11% 22% 17% 4	78411
	Night	39% 3 11% 23% 19% 5%	80087
Seeing	Day	21% 16% 25% 21% 12% 5%	14227
	Night	19% 15% 23% 25% 15% 3	24408

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	15% 5% 2 4 4 3 4 4 5% 7% 47%	2836
	11th to 20th	Day	12% 7% 3 5% 5% 3 4 5% 5% 6% 44%	2840
	21st to end	Day	17% 10% 3 6% 5% 3 4 3 4 5% 39%	3124
February	1st to 10th	Day	11% 6% 3 6% 6% 5% 5% 5% 6% 6% 41%	1701
	11th to 20th	Day	15% 7% 3 5% 6% 3 5% 4 5% 7% 40%	1645
	21st to end	Day	17% 7% 2 6% 5% 4 5% 4 4 6% 39%	1538
March	1st to 10th	Day	13% 6% 2 4 3 3 4 4 6% 7% 48%	1980
	11th to 20th	Day	15% 8% 3 6% 5% 3 5% 5% 5% 7% 37%	1980
	21st to end	Day	16% 7% 3 6% 6% 3 5% 4 5% 6% 38%	2178
April	1st to 10th	Day	8% 4 2 5% 5% 4 5% 5% 6% 9% 47%	2024
	11th to 20th	Day	13% 6% 2 5% 5% 3 4 4 5% 8% 44%	2134
	21st to end	Day	16% 6% 3 6% 6% 3 5% 5% 5% 6% 39%	2292
May	1st to 10th	Day	14% 6% 3 6% 6% 4 5% 6% 7% 8% 35%	2340
	11th to 20th	Day	17% 6% 4 7% 6% 4 5% 5% 7% 7% 32%	2301
	21st to end	Day	15% 6% 3 5% 6% 4 6% 6% 7% 9% 34%	2531
June	1st to 10th	Day	11% 6% 3 5% 6% 4 6% 7% 7% 10% 36%	2340
	11th to 20th	Day	9% 5% 2 6% 6% 4 7% 7% 8% 11% 35%	2340
	21st to end	Day	9% 4 3 6% 7% 4 7% 7% 8% 9% 36%	2340
July	1st to 10th	Day	9% 5% 4 6% 8% 5% 7% 8% 9% 9% 31%	2340
	11th to 20th	Day	8% 5% 3 6% 8% 5% 7% 7% 8% 12% 31%	2340
	21st to end	Day	10% 7% 3 7% 8% 6% 7% 8% 7% 9% 26%	2547
August	1st to 10th	Day	13% 6% 3 7% 6% 5% 7% 7% 8% 10% 29%	2327
	11th to 20th	Day	12% 6% 3 7% 7% 4 8% 8% 8% 10% 27%	2303
	21st to end	Day	13% 7% 2 5% 5% 4 6% 6% 7% 11% 34%	2408
September	1st to 10th	Day	14% 5% 3 5% 5% 3 4 5% 7% 7% 42%	2094
	11th to 20th	Day	16% 7% 2 5% 6% 3 5% 6% 5% 8% 36%	1980
	21st to end	Day	23% 7% 3 5% 5% 3 4 4 5% 7% 36%	1980
October	1st to 10th	Day	17% 4 2 4 5% 3 4 4 4 5% 48%	1828
	11th to 20th	Day	14% 5% 2 4 3 3 4 4 5% 6% 51%	1800
	21st to end	Day	14% 5% 2 5% 5% 2 3 3 4 7% 51%	1980
November	1st to 10th	Day	11% 6% 2 4 3 2 3 4 4 6% 54%	1857
	11th to 20th	Day	13% 5% 2 4 3 3 4 4 4 7% 50%	1744
	21st to end	Day	12% 5% 2 4 5% 3 4 4 6% 6% 48%	1710
December	1st to 10th	Day	11% 8% 3 6% 7% 4 6% 5% 5% 7% 37%	1710
	11th to 20th	Day	13% 5% 2 4 4 3 3 4 5% 8% 51%	2153
	21st to end	Day	17% 8% 3 5% 5% 3 6% 6% 6% 7% 36%	3124
January	1st to 10th	Night	12% 6% 3 4 4 3 4 4 5% 7% 48%	4109
	11th to 20th	Night	13% 6% 2 5% 4 3 5% 4 4 5% 48%	4120
	21st to end	Night	19% 7% 3 4 4 3 4 4 5% 6% 41%	4532
February	1st to 10th	Night	13% 6% 3 5% 4 3 5% 4 6% 8% 44%	2464
	11th to 20th	Night	15% 8% 4 6% 5% 3 4 4 4 6% 41%	2199
	21st to end	Night	13% 6% 3 5% 6% 3 5% 5% 6% 7% 41%	1716
March	1st to 10th	Night	12% 4 2 4 3 3 5% 4 5% 6% 50%	1980
	11th to 20th	Night	16% 6% 3 4 4 4 5% 6% 5% 8% 39%	1980
	21st to end	Night	16% 5% 2 5% 5% 4 5% 5% 5% 6% 42%	2178
April	1st to 10th	Night	10% 7% 3 5% 5% 3 4 5% 5% 7% 46%	1935
	11th to 20th	Night	13% 5% 2 5% 4 2 5% 4 4 8% 47%	1775
	21st to end	Night	16% 4 1 4 5% 2 3 5% 6% 6% 47%	1683
May	1st to 10th	Night	12% 6% 3 5% 5% 3 5% 5% 6% 7% 43%	1620
	11th to 20th	Night	14% 7% 3 6% 5% 4 5% 5% 6% 9% 37%	1592
	21st to end	Night	16% 5% 2 4 5% 3 5% 4 6% 10% 41%	1744
June	1st to 10th	Night	10% 4 2 4 5% 4 5% 6% 8% 11% 41%	1620
	11th to 20th	Night	10% 6% 2 5% 4 2 4 5% 7% 9% 46%	1620
	21st to end	Night	8% 4 2 4 5% 4 5% 5% 8% 11% 45%	1620
July	1st to 10th	Night	8% 5% 2 5% 5% 3 5% 6% 8% 10% 42%	1620
	11th to 20th	Night	5% 4 2 5% 5% 4 6% 5% 9% 12% 44%	1620
	21st to end	Night	6% 4 2 4 5% 5% 7% 7% 9% 13% 38%	1771
August	1st to 10th	Night	13% 6% 2 6% 6% 3 5% 6% 8% 10% 35%	1611
	11th to 20th	Night	12% 5% 2 6% 6% 3 5% 6% 8% 9% 39%	1598
	21st to end	Night	10% 4 2 5% 7% 4 5% 5% 7% 11% 40%	1928
September	1st to 10th	Night	11% 6% 2 5% 5% 3 4 5% 6% 7% 47%	1862
	11th to 20th	Night	15% 8% 2 5% 4 3 4 5% 5% 6% 43%	1980
	21st to end	Night	19% 8% 2 5% 5% 3 5% 3 4 6% 40%	1980
October	1st to 10th	Night	15% 6% 2 5% 4 2 3 3 5% 6% 48%	2130
	11th to 20th	Night	14% 5% 2 3 4 2 4 4 4 7% 51%	2160
	21st to end	Night	13% 4 2 4 4 2 3 4 4 5% 55%	2376
November	1st to 10th	Night	14% 6% 3 4 4 2 4 4 4 5% 52%	2221
	11th to 20th	Night	12% 4 2 3 4 2 4 4 5% 7% 52%	2432
	21st to end	Night	13% 4 2 4 4 2 4 5% 6% 7% 49%	2470
December	1st to 10th	Night	13% 7% 3 5% 6% 2 4 5% 6% 6% 42%	2470
	11th to 20th	Night	13% 6% 2 4 4 3 4 5% 5% 7% 46%	3042
	21st to end	Night	17% 6% 2 5% 5% 3 5% 6% 6% 7% 38%	4532

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	37% 2 6% 24% 24% 7%	2837
	11th to 20th	Day	41% 2 5% 20% 27% 5%	2840
	21st to end	Day	49% 1 5% 19% 22% 5%	3124
February	1st to 10th	Day	42% 3 11% 22% 20% 4	1701
	11th to 20th	Day	43% 4 8% 23% 18% 5%	1654
	21st to end	Day	46% 3 11% 16% 18% 7%	1538
March	1st to 10th	Day	35% 2 9% 25% 22% 7%	1980
	11th to 20th	Day	46% 4 9% 19% 17% 5%	1980
	21st to end	Day	47% 4 9% 23% 14% 4	2178
April	1st to 10th	Day	32% 4 12% 25% 20% 7%	2024
	11th to 20th	Day	39% 3 12% 22% 19% 6%	2134
	21st to end	Day	45% 4 11% 24% 13% 3	2292
May	1st to 10th	Day	45% 4 17% 18% 14% 3	2340
	11th to 20th	Day	50% 5% 14% 20% 9% 2	2305
	21st to end	Day	45% 5% 15% 27% 8%	2531
June	1st to 10th	Day	41% 6% 16% 25% 11% 1	2340
	11th to 20th	Day	40% 7% 17% 20% 14% 2	2340
	21st to end	Day	42% 6% 15% 24% 11% 2	2340
July	1st to 10th	Day	46% 7% 16% 19% 11% 2	2275
	11th to 20th	Day	41% 7% 21% 17% 12% 1	2271
	21st to end	Day	50% 6% 16% 19% 8% 1	2405
August	1st to 10th	Day	48% 6% 16% 22% 7% 1	2314
	11th to 20th	Day	48% 7% 15% 21% 9% 1	2303
	21st to end	Day	43% 6% 17% 20% 11% 3	2408
September	1st to 10th	Day	40% 5% 13% 22% 17% 4	2094
	11th to 20th	Day	45% 3 8% 25% 16% 2	1980
	21st to end	Day	50% 3 8% 20% 17% 2	1980
October	1st to 10th	Day	38% 4 8% 24% 21% 5%	1828
	11th to 20th	Day	34% 2 8% 28% 22% 6%	1800
	21st to end	Day	36% 2 6% 27% 22% 7%	1980
November	1st to 10th	Day	32% 2 9% 22% 28% 6%	1857
	11th to 20th	Day	35% 2 7% 24% 25% 7%	1744
	21st to end	Day	35% 2 8% 24% 26% 4	1710
December	1st to 10th	Day	46% 3 9% 18% 19% 4	1710
	11th to 20th	Day	34% 2 8% 22% 25% 9%	2150
	21st to end	Day	48% 2 6% 24% 18% 3	3124
January	1st to 10th	Night	37% 1 8% 21% 27% 7%	4109
	11th to 20th	Night	40% 2 7% 18% 26% 7%	4120
	21st to end	Night	45% 1 6% 20% 21% 6%	4532
February	1st to 10th	Night	39% 2 9% 26% 20% 3	2464
	11th to 20th	Night	45% 2 8% 21% 17% 7%	2201
	21st to end	Night	42% 3 9% 24% 16% 6%	1716
March	1st to 10th	Night	34% 4 8% 25% 22% 7%	1980
	11th to 20th	Night	44% 3 11% 22% 18% 3	1980
	21st to end	Night	42% 5% 10% 22% 17% 4	2178
April	1st to 10th	Night	38% 3 11% 22% 22% 4	1935
	11th to 20th	Night	37% 3 11% 21% 22% 6%	1775
	21st to end	Night	36% 3 12% 30% 16% 3	1683
May	1st to 10th	Night	40% 5% 14% 26% 13% 2	1620
	11th to 20th	Night	45% 4 15% 23% 11% 1	1593
	21st to end	Night	40% 5% 21% 26% 8% 1	1745
June	1st to 10th	Night	36% 7% 17% 27% 12% 1	1620
	11th to 20th	Night	35% 6% 20% 25% 13% 2	1620
	21st to end	Night	32% 8% 18% 26% 13% 3	1620
July	1st to 10th	Night	37% 7% 19% 22% 11% 5%	1575
	11th to 20th	Night	32% 6% 24% 23% 12% 2	1566
	21st to end	Night	34% 6% 23% 27% 10%	1672
August	1st to 10th	Night	43% 6% 20% 20% 10% 1	1600
	11th to 20th	Night	40% 6% 18% 24% 11% 1	1598
	21st to end	Night	39% 5% 18% 25% 10% 3	1928
September	1st to 10th	Night	37% 6% 14% 22% 16% 5%	1862
	11th to 20th	Night	42% 4 9% 24% 19% 2	1980
	21st to end	Night	48% 3 7% 21% 17% 3	1980
October	1st to 10th	Night	39% 3 8% 24% 23% 3	2130
	11th to 20th	Night	35% 2 7% 29% 21% 5%	2160
	21st to end	Night	32% 1 6% 26% 25% 9%	2376
November	1st to 10th	Night	36% 2 8% 21% 25% 8%	2221
	11th to 20th	Night	33% 2 8% 22% 25% 10%	2432
	21st to end	Night	33% 3 8% 26% 24% 6%	2470
December	1st to 10th	Night	42% 3 7% 24% 19% 4	2470
	11th to 20th	Night	37% 3 7% 20% 24% 9%	3044
	21st to end	Night	45% 2 8% 22% 22% 2	4532

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	34% 29% 27% 9% 2	270
	11th to 20th	Day	38% 30% 24% 7% 1	270
	21st to end	Day	34% 32% 29% 3 2	297
February	1st to 10th	Day	29% 32% 27% 11% 1	267
	11th to 20th	Day	47% 27% 23% 3	240
	21st to end	Day	36% 28% 24% 10% 2	256
March	1st to 10th	Day	27% 30% 27% 12% 4	420
	11th to 20th	Day	27% 29% 28% 12% 3 1	420
	21st to end	Day	27% 27% 30% 12% 5%	462
April	1st to 10th	Day	22% 28% 27% 15% 8%	420
	11th to 20th	Day	25% 17% 25% 21% 8% 3	412
	21st to end	Day	27% 16% 33% 15% 7% 2	420
May	1st to 10th	Day	25% 18% 31% 15% 6% 4	423
	11th to 20th	Day	21% 12% 29% 21% 12% 5%	447
	21st to end	Day	18% 8% 24% 25% 18% 7%	485
June	1st to 10th	Day	14% 9% 28% 29% 14% 6%	450
	11th to 20th	Day	12% 10% 21% 31% 17% 8%	450
	21st to end	Day	11% 8% 29% 31% 15% 5%	450
July	1st to 10th	Day	13% 5% 17% 32% 23% 10%	445
	11th to 20th	Day	7% 3 17% 38% 25% 10%	444
	21st to end	Day	11% 5% 21% 28% 24% 11%	488
August	1st to 10th	Day	14% 8% 22% 22% 19% 14%	446
	11th to 20th	Day	12% 5% 16% 30% 24% 13%	439
	21st to end	Day	14% 5% 14% 30% 22% 15%	495
September	1st to 10th	Day	16% 3 19% 25% 24% 13%	450
	11th to 20th	Day	17% 6% 16% 30% 22% 9%	450
	21st to end	Day	26% 10% 21% 25% 13% 5%	450
October	1st to 10th	Day	23% 9% 21% 27% 15% 5%	450
	11th to 20th	Day	18% 19% 24% 22% 14% 3	450
	21st to end	Day	20% 19% 30% 21% 7% 3	495
November	1st to 10th	Day	22% 17% 27% 22% 11% 2	455
	11th to 20th	Day	26% 23% 26% 18% 6% 1	304
	21st to end	Day	26% 23% 30% 16% 3 1	270
December	1st to 10th	Day	24% 31% 34% 9% 1	270
	11th to 20th	Day	27% 27% 30% 14% 2	270
	21st to end	Day	31% 22% 30% 13% 4	297
January	1st to 10th	Night	22% 31% 28% 16% 3	760
	11th to 20th	Night	25% 25% 30% 17% 2	760
	21st to end	Night	22% 25% 33% 18% 2	836
February	1st to 10th	Night	23% 24% 30% 21% 2	759
	11th to 20th	Night	29% 31% 27% 13% 1	703
	21st to end	Night	24% 25% 31% 18% 1	592
March	1st to 10th	Night	20% 25% 32% 19% 3	720
	11th to 20th	Night	25% 23% 28% 18% 7% 1	720
	21st to end	Night	23% 19% 31% 20% 6%	792
April	1st to 10th	Night	24% 20% 29% 22% 6%	720
	11th to 20th	Night	21% 16% 32% 20% 10% 1	711
	21st to end	Night	19% 15% 31% 27% 8% 1	603
May	1st to 10th	Night	17% 14% 31% 24% 13% 1	540
	11th to 20th	Night	17% 9% 26% 27% 19% 2	531
	21st to end	Night	18% 4 16% 29% 25% 7%	584
June	1st to 10th	Night	13% 3 20% 35% 27% 3	540
	11th to 20th	Night	15% 4 17% 29% 29% 6%	540
	21st to end	Night	9% 4 16% 38% 27% 5%	540
July	1st to 10th	Night	11% 2 11% 37% 33% 6%	525
	11th to 20th	Night	7% 2 11% 35% 38% 7%	522
	21st to end	Night	7% 3 13% 38% 33% 6%	591
August	1st to 10th	Night	16% 3 11% 34% 31% 5%	537
	11th to 20th	Night	14% 3 9% 33% 35% 6%	534
	21st to end	Night	11% 3 12% 27% 37% 9%	740
September	1st to 10th	Night	14% 4 11% 32% 31% 8%	720
	11th to 20th	Night	18% 5% 12% 29% 30% 6%	720
	21st to end	Night	25% 7% 18% 25% 22% 2	720
October	1st to 10th	Night	19% 11% 18% 22% 23% 7%	720
	11th to 20th	Night	20% 12% 24% 25% 15% 2	720
	21st to end	Night	18% 14% 27% 27% 12% 2	792
November	1st to 10th	Night	21% 12% 26% 25% 13% 3	740
	11th to 20th	Night	19% 19% 26% 26% 9% 1	760
	21st to end	Night	18% 21% 26% 22% 11% 1	760
December	1st to 10th	Night	22% 25% 24% 23% 6%	760
	11th to 20th	Night	18% 26% 27% 23% 5% 1	760
	21st to end	Night	25% 23% 23% 24% 5%	836

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