Millers Tavern
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Millers Tavern clear sky chart from 2005-11-06 to 2026-05-02.

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	13% 6% 2 6% 4 4 5% 4 6% 8% 42%	131643
	Night	14% 6% 2 6% 4 4 4 3 5% 7% 45%	130852
Transparency	Day	39% 5% 12% 22% 18% 4	135237
	Night	39% 4 10% 23% 19% 5%	135328
Seeing	Day	19% 13% 28% 23% 13% 4	17019
	Night	17% 11% 29% 29% 12% 1	26714

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 5% 3 3 4 3 4 6% 50%	4979
	11th to 20th	Day	13% 8% 2 5% 3 3 3 2 4 4 53%	5280
	21st to end	Day	13% 8% 3 7% 3 3 5% 3 5% 5% 44%	5780
February	1st to 10th	Day	13% 7% 3 7% 4 5% 4 4 6% 7% 40%	1890
	11th to 20th	Day	22% 7% 1 5% 3 3 4 3 6% 6% 41%	1941
	21st to end	Day	17% 8% 3 7% 5% 4 4 3 4 5% 39%	1730
March	1st to 10th	Day	18% 7% 2 6% 4 4 5% 4 5% 6% 38%	4971
	11th to 20th	Day	11% 5% 2 5% 3 3 4 4 5% 7% 52%	5090
	21st to end	Day	17% 6% 2 6% 4 4 4 3 5% 7% 42%	5679
April	1st to 10th	Day	11% 6% 2 5% 4 4 3 3 5% 7% 49%	2520
	11th to 20th	Day	12% 6% 2 5% 4 4 4 3 5% 8% 47%	2494
	21st to end	Day	15% 7% 2 5% 5% 3 5% 4 5% 8% 43%	2520
May	1st to 10th	Day	15% 7% 3 7% 5% 5% 5% 5% 7% 10% 32%	5636
	11th to 20th	Day	19% 7% 2 6% 5% 4 4 5% 6% 9% 32%	6039
	21st to end	Day	15% 5% 2 6% 4 4 5% 4 6% 9% 40%	6934
June	1st to 10th	Day	10% 5% 2 6% 5% 5% 5% 5% 7% 9% 42%	2800
	11th to 20th	Day	11% 5% 2 5% 4 5% 5% 4 8% 10% 41%	2800
	21st to end	Day	8% 5% 2 7% 5% 5% 5% 4 6% 10% 42%	2800
July	1st to 10th	Day	8% 5% 2 6% 5% 5% 5% 5% 7% 12% 42%	6360
	11th to 20th	Day	12% 6% 3 7% 6% 5% 7% 6% 10% 12% 26%	5998
	21st to end	Day	9% 5% 2 6% 5% 5% 6% 5% 7% 10% 41%	6424
August	1st to 10th	Day	16% 8% 3 8% 4 5% 6% 5% 8% 11% 28%	4234
	11th to 20th	Day	10% 5% 3 8% 5% 5% 6% 4 7% 10% 38%	3924
	21st to end	Day	8% 5% 2 5% 3 4 5% 4 6% 10% 48%	4312
September	1st to 10th	Day	13% 5% 2 6% 4 5% 5% 3 6% 8% 44%	2400
	11th to 20th	Day	12% 7% 3 6% 4 4 4 4 6% 7% 43%	2400
	21st to end	Day	20% 9% 3 6% 4 4 4 3 5% 7% 36%	2110
October	1st to 10th	Day	14% 6% 3 5% 4 4 3 3 5% 7% 46%	2000
	11th to 20th	Day	17% 5% 1 4 3 3 3 2 5% 5% 52%	2000
	21st to end	Day	13% 5% 2 5% 3 3 3 3 4 6% 53%	2200
November	1st to 10th	Day	13% 5% 2 4 3 3 3 3 4 6% 54%	1983
	11th to 20th	Day	14% 5% 1 6% 3 3 3 3 5% 6% 50%	1890
	21st to end	Day	14% 5% 2 5% 4 3 3 2 5% 4 52%	1727
December	1st to 10th	Day	12% 5% 2 5% 3 3 3 3 5% 6% 52%	2680
	11th to 20th	Day	19% 7% 3 5% 3 3 3 2 3 5% 47%	3070
	21st to end	Day	14% 6% 2 6% 4 4 4 3 5% 8% 44%	4048
January	1st to 10th	Night	12% 6% 2 5% 3 3 4 3 5% 6% 48%	7898
	11th to 20th	Night	14% 6% 2 5% 3 3 3 2 3 5% 54%	7680
	21st to end	Night	16% 6% 2 5% 3 4 3 3 4 5% 49%	8401
February	1st to 10th	Night	15% 7% 2 5% 5% 4 4 4 5% 6% 43%	2730
	11th to 20th	Night	20% 7% 2 5% 4 4 3 3 5% 5% 43%	2564
	21st to end	Night	17% 6% 2 6% 4 4 3 4 5% 6% 46%	2076
March	1st to 10th	Night	18% 6% 2 6% 3 3 3 3 4 6% 46%	5086
	11th to 20th	Night	13% 5% 3 5% 4 3 3 3 5% 6% 50%	5090
	21st to end	Night	13% 7% 2 6% 4 3 4 3 4 6% 48%	5495
April	1st to 10th	Night	14% 7% 2 6% 4 4 4 2 4 8% 45%	2100
	11th to 20th	Night	12% 5% 2 5% 4 3 4 3 5% 7% 50%	2075
	21st to end	Night	15% 6% 2 6% 4 4 4 4 5% 7% 44%	2100
May	1st to 10th	Night	16% 8% 3 8% 5% 4 5% 5% 6% 9% 33%	4325
	11th to 20th	Night	22% 7% 3 6% 4 4 4 4 5% 8% 34%	3850
	21st to end	Night	16% 7% 2 6% 4 4 4 4 6% 8% 38%	3920
June	1st to 10th	Night	10% 6% 2 6% 6% 5% 6% 5% 5% 9% 41%	1600
	11th to 20th	Night	11% 7% 2 5% 5% 4 5% 4 7% 9% 40%	1600
	21st to end	Night	7% 5% 2 5% 4 4 5% 6% 6% 11% 44%	1600
July	1st to 10th	Night	10% 6% 2 7% 5% 5% 5% 4 8% 10% 38%	3598
	11th to 20th	Night	12% 7% 3 7% 5% 6% 5% 5% 8% 12% 29%	3955
	21st to end	Night	9% 6% 2 8% 6% 6% 6% 5% 8% 8% 36%	4427
August	1st to 10th	Night	16% 7% 3 8% 4 4 5% 4 7% 9% 32%	2915
	11th to 20th	Night	11% 6% 2 7% 5% 4 5% 5% 7% 9% 38%	3089
	21st to end	Night	10% 5% 2 5% 4 4 4 4 5% 8% 50%	3586
September	1st to 10th	Night	13% 5% 2 6% 4 4 5% 3 6% 8% 44%	2000
	11th to 20th	Night	11% 7% 2 6% 4 4 4 3 6% 7% 47%	2000
	21st to end	Night	21% 8% 3 6% 4 4 3 4 5% 6% 36%	2285
October	1st to 10th	Night	14% 7% 2 5% 3 4 4 3 5% 6% 48%	2400
	11th to 20th	Night	17% 5% 2 5% 3 3 2 3 4 5% 50%	2400
	21st to end	Night	14% 5% 2 5% 4 3 3 2 4 6% 52%	2640
November	1st to 10th	Night	12% 6% 2 5% 4 3 3 3 4 6% 51%	2534
	11th to 20th	Night	16% 7% 2 4 3 3 4 4 4 5% 48%	2730
	21st to end	Night	12% 5% 1 5% 3 4 4 3 5% 7% 51%	2888
December	1st to 10th	Night	10% 5% 2 4 3 3 3 3 5% 7% 55%	4720
	11th to 20th	Night	20% 7% 3 6% 4 4 4 3 5% 6% 40%	5345
	21st to end	Night	14% 7% 2 6% 3 3 3 3 5% 7% 45%	7150

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 8% 26% 19% 8%	4980
	11th to 20th	Day	36% 2 5% 19% 27% 11%	5280
	21st to end	Day	43% 3 6% 27% 18% 3	5780
February	1st to 10th	Day	42% 6% 10% 26% 14% 3	1890
	11th to 20th	Day	43% 4 8% 21% 20% 4	1950
	21st to end	Day	47% 4 9% 19% 16% 4	1730
March	1st to 10th	Day	46% 3 8% 17% 18% 7%	4971
	11th to 20th	Day	32% 4 9% 24% 22% 9%	5090
	21st to end	Day	42% 4 12% 17% 19% 6%	5679
April	1st to 10th	Day	34% 5% 12% 22% 20% 7%	2520
	11th to 20th	Day	35% 4 11% 22% 21% 6%	2494
	21st to end	Day	40% 5% 11% 23% 15% 5%	2520
May	1st to 10th	Day	46% 7% 16% 18% 12% 1	5668
	11th to 20th	Day	47% 6% 14% 23% 10% 1	6043
	21st to end	Day	39% 7% 13% 23% 16% 2	6949
June	1st to 10th	Day	36% 8% 16% 24% 14% 2	2800
	11th to 20th	Day	36% 9% 15% 23% 16% 1	2800
	21st to end	Day	36% 8% 14% 23% 17% 2	2800
July	1st to 10th	Day	35% 6% 22% 20% 13% 3	6290
	11th to 20th	Day	49% 7% 23% 16% 5% 1	5926
	21st to end	Day	38% 6% 16% 21% 20% 1	6240
August	1st to 10th	Day	49% 7% 16% 22% 7%	4221
	11th to 20th	Day	42% 5% 14% 24% 14%	3962
	21st to end	Day	32% 5% 15% 27% 20% 2	4312
September	1st to 10th	Day	38% 7% 13% 17% 21% 3	2400
	11th to 20th	Day	40% 6% 9% 23% 20% 3	2400
	21st to end	Day	49% 5% 9% 19% 13% 4	2110
October	1st to 10th	Day	39% 3 7% 19% 27% 5%	3260
	11th to 20th	Day	27% 2 5% 20% 35% 11%	3240
	21st to end	Day	22% 2 9% 28% 27% 12%	3538
November	1st to 10th	Day	33% 4 8% 28% 22% 4	1983
	11th to 20th	Day	36% 3 9% 23% 22% 7%	1890
	21st to end	Day	36% 3 8% 27% 22% 4	1727
December	1st to 10th	Day	34% 2 8% 30% 19% 7%	2680
	11th to 20th	Day	42% 2 11% 23% 16% 5%	3066
	21st to end	Day	39% 4 12% 28% 16% 1	4048
January	1st to 10th	Night	37% 2 10% 22% 22% 7%	7899
	11th to 20th	Night	35% 3 4 23% 26% 9%	7680
	21st to end	Night	39% 2 5% 29% 20% 5%	8401
February	1st to 10th	Night	41% 5% 10% 23% 17% 2	2730
	11th to 20th	Night	44% 4 8% 20% 19% 6%	2566
	21st to end	Night	41% 4 9% 22% 17% 7%	2076
March	1st to 10th	Night	42% 2 7% 20% 21% 7%	5086
	11th to 20th	Night	36% 3 7% 21% 24% 9%	5090
	21st to end	Night	40% 3 8% 23% 20% 7%	5495
April	1st to 10th	Night	40% 5% 9% 18% 22% 5%	2100
	11th to 20th	Night	34% 6% 11% 22% 22% 5%	2075
	21st to end	Night	39% 6% 11% 22% 17% 5%	2100
May	1st to 10th	Night	48% 6% 16% 19% 9% 2	4355
	11th to 20th	Night	49% 7% 10% 24% 10% 1	3851
	21st to end	Night	43% 6% 14% 23% 13% 1	3927
June	1st to 10th	Night	39% 9% 13% 22% 16% 1	1600
	11th to 20th	Night	37% 11% 14% 22% 15% 1	1600
	21st to end	Night	33% 9% 14% 23% 17% 3	1600
July	1st to 10th	Night	41% 8% 17% 18% 13% 3	3560
	11th to 20th	Night	46% 9% 24% 16% 4 1	3907
	21st to end	Night	44% 6% 12% 22% 15%	4297
August	1st to 10th	Night	48% 7% 16% 23% 7%	2904
	11th to 20th	Night	41% 6% 18% 23% 12%	3117
	21st to end	Night	32% 6% 11% 26% 24% 1	3586
September	1st to 10th	Night	36% 9% 15% 18% 17% 5%	2000
	11th to 20th	Night	37% 6% 10% 25% 21% 2	2000
	21st to end	Night	49% 6% 9% 17% 16% 3	2285
October	1st to 10th	Night	39% 3 10% 20% 23% 6%	3920
	11th to 20th	Night	26% 2 7% 22% 30% 12%	3899
	21st to end	Night	23% 2 5% 31% 27% 12%	4252
November	1st to 10th	Night	36% 4 9% 23% 23% 5%	2534
	11th to 20th	Night	38% 4 8% 20% 20% 9%	2730
	21st to end	Night	33% 4 9% 26% 23% 5%	2888
December	1st to 10th	Night	30% 3 9% 28% 25% 4	4720
	11th to 20th	Night	47% 3 11% 20% 14% 6%	5348
	21st to end	Night	38% 4 12% 29% 16% 2	7150

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	28% 23% 31% 13% 4 1	278
	11th to 20th	Day	27% 32% 29% 10% 2	330
	21st to end	Day	25% 29% 34% 10% 2	363
February	1st to 10th	Day	22% 26% 38% 11% 3	330
	11th to 20th	Day	35% 25% 27% 13% 1	428
	21st to end	Day	32% 19% 30% 15% 4	446
March	1st to 10th	Day	23% 23% 33% 16% 5%	540
	11th to 20th	Day	24% 24% 31% 15% 5% 1	540
	21st to end	Day	23% 18% 39% 15% 4 1	594
April	1st to 10th	Day	22% 23% 33% 16% 6% 1	540
	11th to 20th	Day	17% 17% 36% 20% 7% 3	532
	21st to end	Day	21% 16% 34% 21% 7% 2	540
May	1st to 10th	Day	20% 15% 34% 21% 8% 2	507
	11th to 20th	Day	20% 12% 32% 23% 11% 2	527
	21st to end	Day	20% 7% 26% 27% 15% 4	573
June	1st to 10th	Day	13% 8% 30% 29% 16% 4	530
	11th to 20th	Day	13% 7% 25% 32% 17% 5%	530
	21st to end	Day	9% 8% 26% 32% 20% 5%	530
July	1st to 10th	Day	11% 3 20% 34% 25% 7%	525
	11th to 20th	Day	7% 2 17% 40% 25% 9%	524
	21st to end	Day	10% 2 22% 34% 23% 9%	576
August	1st to 10th	Day	15% 2 19% 31% 25% 7%	526
	11th to 20th	Day	11% 4 18% 33% 24% 9%	519
	21st to end	Day	9% 3 20% 31% 21% 15%	583
September	1st to 10th	Day	13% 5% 23% 28% 19% 12%	530
	11th to 20th	Day	14% 6% 22% 28% 20% 10%	530
	21st to end	Day	29% 9% 24% 23% 11% 5%	530
October	1st to 10th	Day	20% 7% 23% 24% 17% 8%	530
	11th to 20th	Day	19% 13% 27% 24% 16% 2	530
	21st to end	Day	17% 13% 37% 20% 9% 4	583
November	1st to 10th	Day	17% 14% 32% 23% 12% 3	496
	11th to 20th	Day	19% 16% 32% 23% 10%	430
	21st to end	Day	20% 16% 34% 20% 8% 1	267
December	1st to 10th	Day	23% 20% 36% 15% 4 2	220
	11th to 20th	Day	23% 17% 32% 20% 7%	220
	21st to end	Day	21% 21% 32% 18% 7% 2	242
January	1st to 10th	Night	19% 20% 39% 18% 3	840
	11th to 20th	Night	21% 19% 33% 23% 4	840
	21st to end	Night	20% 18% 38% 23% 1	924
February	1st to 10th	Night	20% 16% 39% 23% 3	840
	11th to 20th	Night	26% 23% 34% 16% 2	823
	21st to end	Night	21% 21% 35% 20% 3	692
March	1st to 10th	Night	19% 18% 37% 23% 3	840
	11th to 20th	Night	23% 18% 33% 19% 5% 1	840
	21st to end	Night	18% 18% 40% 20% 3	924
April	1st to 10th	Night	17% 19% 39% 21% 3	840
	11th to 20th	Night	15% 14% 38% 25% 7%	831
	21st to end	Night	19% 10% 35% 29% 6%	840
May	1st to 10th	Night	18% 11% 36% 27% 7% 1	733
	11th to 20th	Night	18% 7% 31% 34% 9% 1	513
	21st to end	Night	17% 3 22% 37% 18% 2	433
June	1st to 10th	Night	12% 4 20% 43% 21% 1	400
	11th to 20th	Night	14% 5% 22% 42% 16% 2	400
	21st to end	Night	9% 4 21% 45% 19% 2	400
July	1st to 10th	Night	12% 2 18% 38% 29% 2	390
	11th to 20th	Night	7% 2 13% 40% 33% 4	535
	21st to end	Night	7% 3 18% 42% 26% 4	657
August	1st to 10th	Night	11% 3 15% 40% 27% 4	597
	11th to 20th	Night	13% 3 14% 41% 25% 4	718
	21st to end	Night	12% 3 14% 38% 29% 5%	880
September	1st to 10th	Night	16% 2 15% 37% 26% 4	800
	11th to 20th	Night	14% 4 16% 37% 25% 4	800
	21st to end	Night	26% 5% 21% 29% 18% 2	800
October	1st to 10th	Night	17% 5% 23% 30% 23% 4	800
	11th to 20th	Night	20% 8% 27% 29% 15% 1	800
	21st to end	Night	16% 11% 31% 27% 14% 1	880
November	1st to 10th	Night	15% 9% 30% 31% 12% 2	820
	11th to 20th	Night	20% 14% 30% 29% 8%	840
	21st to end	Night	14% 14% 33% 28% 9% 1	840
December	1st to 10th	Night	23% 13% 34% 21% 8% 1	840
	11th to 20th	Night	19% 13% 36% 27% 5%	840
	21st to end	Night	19% 16% 29% 31% 5%	924

Page generated at 2026-04-29 02:21:46. Version ac07

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