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Talmage Observatory at Starfield
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Talmage Observatory at Starfield clear sky chart from 2005-11-06 to 2025-11-03.

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	18% 8% 2 6% 4 4 4 3 5% 7% 38%	126497
	Night	17% 8% 3 6% 4 4 4 3 5% 6% 39%	123543
Transparency	Day	46% 3 11% 23% 15% 3	130017
	Night	46% 3 10% 22% 15% 3	128110
Seeing	Day	23% 16% 33% 19% 7% 2	16263
	Night	22% 13% 31% 26% 8% 1	25049

By Month

Percentage Cloud Cover NE (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% 9% 2 5% 4 5% 6% 3 6% 6% 40%	3597
	11th to 20th	Day	14% 7% 3 5% 4 4 3 3 4 6% 45%	3570
	21st to end	Day	14% 9% 3 5% 3 3 4 3 3 5% 47%	3960
February	1st to 10th	Day	16% 9% 3 6% 4 4 5% 4 6% 6% 38%	1797
	11th to 20th	Day	13% 8% 3 7% 4 4 4 4 6% 7% 41%	1948
	21st to end	Day	15% 11% 3 7% 6% 4 3 3 5% 5% 38%	1650
March	1st to 10th	Day	22% 11% 2 6% 4 4 4 3 4 5% 34%	4476
	11th to 20th	Day	17% 11% 3 6% 4 4 3 3 4 6% 39%	4837
	21st to end	Day	27% 9% 3 6% 3 3 3 3 5% 6% 32%	5680
April	1st to 10th	Day	19% 11% 3 6% 4 3 3 2 4 6% 37%	2400
	11th to 20th	Day	17% 7% 2 6% 4 4 5% 4 6% 7% 39%	2442
	21st to end	Day	21% 8% 2 7% 5% 4 4 3 4 5% 36%	2600
May	1st to 10th	Day	33% 11% 3 6% 4 4 4 3 5% 5% 23%	5886
	11th to 20th	Day	20% 9% 3 8% 5% 5% 5% 3 5% 8% 31%	5969
	21st to end	Day	21% 7% 2 6% 4 4 5% 4 6% 7% 33%	6949
June	1st to 10th	Day	21% 7% 3 7% 4 5% 4 4 6% 7% 32%	2800
	11th to 20th	Day	17% 6% 2 6% 4 4 5% 4 5% 8% 39%	2800
	21st to end	Day	20% 7% 3 6% 5% 4 5% 4 6% 8% 34%	2800
July	1st to 10th	Day	16% 7% 3 7% 4 5% 6% 4 6% 9% 32%	6360
	11th to 20th	Day	9% 7% 3 7% 5% 4 5% 5% 7% 10% 38%	6360
	21st to end	Day	15% 6% 2 5% 3 4 4 4 6% 8% 43%	6926
August	1st to 10th	Day	14% 6% 3 7% 5% 4 5% 4 7% 8% 37%	4275
	11th to 20th	Day	16% 9% 3 7% 5% 4 4 3 6% 9% 35%	4175
	21st to end	Day	9% 4 2 5% 5% 4 6% 4 7% 10% 46%	4393
September	1st to 10th	Day	13% 4 1 5% 4 4 4 4 6% 7% 49%	2370
	11th to 20th	Day	13% 6% 2 4 3 3 3 3 4 6% 56%	2200
	21st to end	Day	15% 6% 2 5% 4 3 5% 3 5% 7% 47%	2200
October	1st to 10th	Day	19% 7% 2 6% 4 3 4 3 5% 5% 42%	2200
	11th to 20th	Day	16% 6% 3 5% 4 4 4 3 5% 6% 44%	1934
	21st to end	Day	21% 7% 2 5% 4 3 4 3 4 5% 41%	1980
November	1st to 10th	Day	16% 6% 2 4 3 3 3 3 5% 6% 49%	1779
	11th to 20th	Day	20% 5% 1 4 3 3 3 3 5% 6% 48%	1800
	21st to end	Day	21% 8% 2 5% 3 3 3 3 4 7% 42%	1800
December	1st to 10th	Day	15% 10% 2 5% 4 4 4 3 5% 7% 41%	2638
	11th to 20th	Day	19% 6% 2 5% 4 3 3 2 5% 5% 48%	2986
	21st to end	Day	21% 10% 2 5% 3 3 3 3 5% 6% 37%	3960
January	1st to 10th	Night	14% 7% 2 7% 4 4 4 4 6% 6% 43%	6349
	11th to 20th	Night	12% 9% 3 10% 5% 5% 4 3 5% 6% 37%	6315
	21st to end	Night	15% 9% 3 6% 4 4 4 3 5% 5% 41%	6996
February	1st to 10th	Night	16% 9% 4 7% 4 5% 4 4 5% 5% 38%	2596
	11th to 20th	Night	13% 10% 3 6% 5% 4 5% 4 5% 6% 41%	2338
	21st to end	Night	14% 10% 3 6% 5% 4 4 4 4 6% 41%	1980
March	1st to 10th	Night	25% 9% 2 6% 5% 4 4 3 4 5% 34%	5364
	11th to 20th	Night	14% 10% 3 8% 4 5% 5% 4 5% 6% 37%	5120
	21st to end	Night	26% 8% 2 5% 3 3 4 3 6% 6% 33%	5248
April	1st to 10th	Night	21% 9% 3 5% 4 3 4 4 5% 6% 36%	2000
	11th to 20th	Night	19% 9% 3 5% 4 4 3 3 4 6% 40%	1906
	21st to end	Night	20% 9% 2 6% 5% 4 3 3 4 6% 38%	1800
May	1st to 10th	Night	33% 10% 3 6% 4 4 4 3 5% 6% 23%	4054
	11th to 20th	Night	15% 10% 4 9% 6% 5% 5% 5% 6% 8% 28%	3954
	21st to end	Night	21% 8% 3 7% 5% 5% 4 3 5% 7% 33%	3926
June	1st to 10th	Night	21% 8% 2 7% 5% 4 4 3 6% 6% 34%	1600
	11th to 20th	Night	18% 8% 3 5% 4 4 4 4 5% 7% 39%	1600
	21st to end	Night	21% 6% 2 6% 5% 4 4 4 5% 7% 37%	1600
July	1st to 10th	Night	12% 6% 2 7% 6% 4 6% 4 7% 10% 36%	3600
	11th to 20th	Night	13% 8% 3 7% 4 5% 5% 4 6% 9% 37%	3600
	21st to end	Night	11% 4 2 5% 4 4 4 4 6% 7% 48%	3926
August	1st to 10th	Night	19% 6% 3 7% 5% 5% 5% 4 5% 7% 33%	2840
	11th to 20th	Night	14% 9% 3 6% 4 4 5% 4 6% 7% 36%	2872
	21st to end	Night	10% 4 2 5% 3 4 5% 4 6% 8% 50%	3501
September	1st to 10th	Night	12% 5% 2 5% 4 3 5% 3 5% 5% 51%	2030
	11th to 20th	Night	14% 5% 2 5% 3 3 3 2 5% 7% 52%	2200
	21st to end	Night	17% 5% 2 5% 3 4 4 3 4 6% 47%	2200
October	1st to 10th	Night	18% 7% 2 7% 4 4 5% 3 5% 5% 42%	2200
	11th to 20th	Night	16% 5% 2 6% 4 3 4 3 5% 6% 44%	2463
	21st to end	Night	22% 7% 2 6% 3 4 4 3 5% 5% 38%	2860
November	1st to 10th	Night	16% 6% 2 5% 4 3 4 4 5% 5% 46%	2564
	11th to 20th	Night	18% 6% 1 5% 4 4 3 2 4 5% 47%	2600
	21st to end	Night	17% 7% 3 5% 4 3 4 3 5% 6% 44%	2600
December	1st to 10th	Night	16% 10% 3 6% 4 3 3 3 4 6% 41%	4537
	11th to 20th	Night	23% 7% 2 5% 3 3 3 3 4 4 42%	5208
	21st to end	Night	20% 11% 3 6% 4 4 3 3 4 4 39%	6996

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	44% 2 8% 27% 18% 1	3598
	11th to 20th	Day	42% 3 12% 25% 16% 3	3600
	21st to end	Day	42% 2 7% 22% 21% 5%	3960
February	1st to 10th	Day	46% 3 13% 21% 14% 4	1797
	11th to 20th	Day	42% 5% 11% 23% 14% 4	1957
	21st to end	Day	50% 2 10% 20% 15% 3	1650
March	1st to 10th	Day	55% 2 8% 12% 13% 11%	4479
	11th to 20th	Day	47% 2 15% 20% 12% 4	4837
	21st to end	Day	54% 2 3 16% 17% 7%	5680
April	1st to 10th	Day	50% 3 8% 19% 17% 4	2400
	11th to 20th	Day	44% 5% 11% 22% 15% 4	2442
	21st to end	Day	51% 3 9% 18% 16% 3	2600
May	1st to 10th	Day	64% 3 11% 14% 7% 1	5897
	11th to 20th	Day	53% 4 14% 19% 9% 2	5973
	21st to end	Day	48% 4 14% 21% 11% 1	6949
June	1st to 10th	Day	50% 5% 11% 22% 11%	2800
	11th to 20th	Day	43% 3 13% 22% 16% 3	2800
	21st to end	Day	47% 5% 13% 22% 12% 1	2800
July	1st to 10th	Day	49% 4 12% 22% 12%	6290
	11th to 20th	Day	41% 4 15% 24% 14% 1	6285
	21st to end	Day	39% 3 14% 28% 15% 1	6728
August	1st to 10th	Day	45% 4 16% 25% 10%	4261
	11th to 20th	Day	47% 4 15% 26% 8% 1	4214
	21st to end	Day	33% 3 15% 27% 19% 1	4393
September	1st to 10th	Day	34% 5% 12% 30% 18% 1	2370
	11th to 20th	Day	33% 2 9% 29% 24% 2	2200
	21st to end	Day	38% 5% 9% 27% 19% 2	2200
October	1st to 10th	Day	46% 2 7% 24% 19% 2	3590
	11th to 20th	Day	35% 2 8% 32% 21% 2	3124
	21st to end	Day	36% 2 8% 29% 21% 3	3180
November	1st to 10th	Day	37% 3 13% 27% 18% 2	1779
	11th to 20th	Day	38% 3 10% 22% 23% 4	1800
	21st to end	Day	44% 3 15% 22% 14% 1	1800
December	1st to 10th	Day	44% 2 12% 30% 11% 1	2638
	11th to 20th	Day	41% 3 11% 19% 18% 8%	2986
	21st to end	Day	51% 2 8% 19% 13% 6%	3960
January	1st to 10th	Night	42% 2 9% 33% 13% 2	6349
	11th to 20th	Night	50% 3 11% 21% 12% 3	6360
	21st to end	Night	46% 2 7% 20% 18% 7%	6996
February	1st to 10th	Night	47% 4 11% 19% 15% 3	2596
	11th to 20th	Night	44% 3 10% 21% 17% 4	2340
	21st to end	Night	45% 3 10% 23% 15% 5%	1980
March	1st to 10th	Night	55% 2 8% 13% 15% 7%	5374
	11th to 20th	Night	49% 2 15% 18% 13% 2	5121
	21st to end	Night	52% 2 4 14% 21% 6%	5248
April	1st to 10th	Night	49% 4 9% 18% 16% 4	2000
	11th to 20th	Night	46% 3 8% 22% 18% 2	1906
	21st to end	Night	49% 3 9% 18% 17% 4	1800
May	1st to 10th	Night	63% 3 11% 14% 7% 1	4060
	11th to 20th	Night	54% 4 14% 18% 8% 2	3955
	21st to end	Night	53% 4 13% 19% 10% 1	3927
June	1st to 10th	Night	51% 5% 10% 20% 13% 1	1600
	11th to 20th	Night	44% 5% 13% 21% 14% 2	1600
	21st to end	Night	47% 5% 12% 23% 11% 1	1600
July	1st to 10th	Night	44% 4 14% 25% 13%	3560
	11th to 20th	Night	45% 4 14% 21% 17%	3552
	21st to end	Night	37% 3 13% 33% 14%	3809
August	1st to 10th	Night	51% 5% 12% 21% 10% 1	2830
	11th to 20th	Night	47% 4 14% 23% 12% 1	2899
	21st to end	Night	33% 3 15% 27% 21% 1	3501
September	1st to 10th	Night	35% 5% 11% 28% 20% 1	2030
	11th to 20th	Night	34% 4 9% 29% 22% 2	2200
	21st to end	Night	38% 5% 9% 28% 17% 2	2200
October	1st to 10th	Night	45% 3 11% 23% 16% 2	3590
	11th to 20th	Night	32% 2 9% 28% 25% 4	4012
	21st to end	Night	39% 2 9% 30% 18% 3	4610
November	1st to 10th	Night	39% 4 10% 26% 18% 3	2564
	11th to 20th	Night	41% 3 9% 24% 21% 3	2600
	21st to end	Night	42% 3 14% 25% 14% 2	2600
December	1st to 10th	Night	46% 2 9% 31% 11% 1	4537
	11th to 20th	Night	47% 2 11% 16% 21% 3	5208
	21st to end	Night	51% 2 8% 21% 16% 2	6996

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	27% 26% 30% 16% 3 1	200
	11th to 20th	Day	28% 24% 31% 15% 2 1	200
	21st to end	Day	22% 24% 37% 12% 5%	220
February	1st to 10th	Day	29% 22% 37% 11% 1	375
	11th to 20th	Day	28% 27% 30% 14% 2	496
	21st to end	Day	27% 23% 32% 14% 4	414
March	1st to 10th	Day	30% 21% 34% 12% 3	500
	11th to 20th	Day	27% 26% 32% 11% 4 1	500
	21st to end	Day	29% 21% 32% 12% 4 2	550
April	1st to 10th	Day	35% 23% 26% 10% 5% 1	500
	11th to 20th	Day	31% 23% 27% 12% 6% 1	492
	21st to end	Day	30% 19% 31% 13% 5% 1	500
May	1st to 10th	Day	33% 20% 31% 11% 3 2	503
	11th to 20th	Day	23% 18% 37% 16% 5% 2	527
	21st to end	Day	21% 19% 34% 20% 6% 1	573
June	1st to 10th	Day	22% 16% 36% 18% 6% 1	530
	11th to 20th	Day	18% 19% 35% 20% 5% 2	530
	21st to end	Day	22% 13% 37% 18% 8% 2	530
July	1st to 10th	Day	18% 8% 38% 26% 7% 3	525
	11th to 20th	Day	14% 9% 36% 28% 10% 3	524
	21st to end	Day	16% 6% 40% 27% 9% 2	576
August	1st to 10th	Day	13% 9% 34% 28% 12% 3	526
	11th to 20th	Day	18% 7% 32% 24% 13% 6%	519
	21st to end	Day	13% 9% 34% 28% 10% 5%	583
September	1st to 10th	Day	16% 10% 32% 27% 11% 5%	530
	11th to 20th	Day	18% 11% 29% 25% 10% 8%	530
	21st to end	Day	15% 11% 37% 22% 9% 5%	530
October	1st to 10th	Day	23% 13% 27% 23% 11% 3	530
	11th to 20th	Day	22% 16% 26% 24% 10% 2	442
	21st to end	Day	28% 14% 31% 19% 6% 1	462
November	1st to 10th	Day	24% 14% 32% 22% 7% 1	401
	11th to 20th	Day	28% 18% 31% 19% 4 1	400
	21st to end	Day	28% 20% 29% 17% 5% 1	400
December	1st to 10th	Day	20% 28% 33% 14% 4	225
	11th to 20th	Day	30% 23% 36% 9% 4	200
	21st to end	Day	30% 19% 32% 15% 5%	220
January	1st to 10th	Night	22% 20% 36% 20% 2	800
	11th to 20th	Night	27% 17% 35% 18% 4	800
	21st to end	Night	19% 21% 36% 21% 3	880
February	1st to 10th	Night	23% 19% 40% 17% 2	800
	11th to 20th	Night	22% 20% 37% 18% 2	783
	21st to end	Night	23% 17% 35% 22% 4	660
March	1st to 10th	Night	27% 16% 38% 18% 2	800
	11th to 20th	Night	23% 18% 34% 20% 6%	800
	21st to end	Night	28% 14% 35% 19% 5%	880
April	1st to 10th	Night	29% 16% 32% 20% 4	800
	11th to 20th	Night	24% 15% 33% 22% 5%	722
	21st to end	Night	24% 14% 33% 24% 5%	600
May	1st to 10th	Night	25% 9% 34% 26% 6% 1	600
	11th to 20th	Night	20% 12% 32% 28% 7% 1	565
	21st to end	Night	24% 8% 29% 30% 8% 1	433
June	1st to 10th	Night	23% 7% 29% 29% 10% 1	400
	11th to 20th	Night	21% 5% 28% 32% 13% 1	400
	21st to end	Night	23% 3 25% 38% 12%	400
July	1st to 10th	Night	18% 2 22% 43% 14% 1	390
	11th to 20th	Night	16% 4 21% 40% 19% 1	388
	21st to end	Night	13% 3 20% 48% 14% 2	438
August	1st to 10th	Night	15% 5% 23% 42% 15%	548
	11th to 20th	Night	15% 6% 24% 34% 19% 2	592
	21st to end	Night	15% 5% 23% 37% 17% 2	821
September	1st to 10th	Night	14% 5% 27% 37% 18% 1	800
	11th to 20th	Night	16% 7% 26% 28% 19% 4	800
	21st to end	Night	19% 7% 27% 30% 16% 2	800
October	1st to 10th	Night	22% 10% 25% 27% 16% 1	800
	11th to 20th	Night	19% 11% 31% 27% 11% 1	800
	21st to end	Night	26% 12% 30% 25% 6%	880
November	1st to 10th	Night	19% 13% 35% 25% 7% 1	789
	11th to 20th	Night	22% 18% 32% 21% 6% 1	800
	21st to end	Night	21% 20% 32% 24% 4	800
December	1st to 10th	Night	25% 14% 38% 19% 5%	800
	11th to 20th	Night	25% 19% 32% 21% 3	800
	21st to end	Night	26% 16% 34% 22% 2	880

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