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 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	14% 6% 2 6% 4 4 4 4 6% 8% 42%	104727
	Night	15% 7% 2 6% 4 4 4 3 5% 7% 44%	104269
Transparency	Day	39% 6% 12% 22% 17% 4	108365
	Night	39% 5% 11% 23% 18% 4	108770
Seeing	Day	18% 12% 28% 24% 13% 4	15284
	Night	17% 11% 29% 29% 12% 1	24951

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	17% 6% 2 4 3 3 3 3 3 6% 51%	2731
	11th to 20th	Day	15% 10% 2 6% 4 4 4 3 5% 5% 43%	2840
	21st to end	Day	16% 11% 4 8% 3 3 4 3 5% 5% 37%	3124
February	1st to 10th	Day	14% 7% 3 7% 4 5% 4 5% 6% 7% 38%	1710
	11th to 20th	Day	21% 6% 1 5% 3 3 3 3 6% 6% 43%	1751
	21st to end	Day	17% 8% 3 7% 5% 4 4 3 5% 5% 38%	1570
March	1st to 10th	Day	22% 9% 3 6% 4 4 4 3 4 6% 36%	3391
	11th to 20th	Day	10% 4 1 4 3 3 4 4 6% 7% 53%	3480
	21st to end	Day	21% 6% 2 6% 4 4 4 3 5% 6% 39%	3878
April	1st to 10th	Day	11% 6% 2 5% 4 4 3 4 5% 6% 50%	2280
	11th to 20th	Day	12% 6% 2 5% 4 4 4 3 5% 7% 47%	2254
	21st to end	Day	15% 7% 2 5% 4 3 4 4 5% 8% 42%	2280
May	1st to 10th	Day	17% 7% 3 8% 4 5% 5% 4 7% 9% 31%	3914
	11th to 20th	Day	20% 7% 2 6% 5% 4 4 4 6% 8% 32%	4203
	21st to end	Day	9% 4 2 6% 4 4 5% 4 7% 10% 45%	4823
June	1st to 10th	Day	11% 5% 2 5% 5% 5% 5% 5% 7% 9% 42%	2660
	11th to 20th	Day	10% 5% 2 5% 4 6% 5% 5% 8% 10% 41%	2660
	21st to end	Day	8% 5% 2 7% 5% 5% 6% 4 6% 10% 41%	2660
July	1st to 10th	Day	6% 4 2 6% 5% 5% 5% 5% 8% 12% 42%	4440
	11th to 20th	Day	12% 5% 2 6% 5% 4 6% 5% 8% 11% 34%	4190
	21st to end	Day	11% 6% 3 7% 6% 6% 6% 5% 7% 9% 34%	4466
August	1st to 10th	Day	15% 8% 3 8% 4 5% 6% 5% 8% 11% 28%	4104
	11th to 20th	Day	10% 5% 3 8% 5% 5% 5% 4 7% 10% 39%	3802
	21st to end	Day	8% 5% 2 5% 3 4 5% 4 6% 11% 48%	4180
September	1st to 10th	Day	13% 5% 2 6% 5% 5% 5% 3 6% 8% 43%	2280
	11th to 20th	Day	11% 7% 3 6% 4 5% 4 4 6% 7% 44%	2280
	21st to end	Day	20% 9% 3 6% 4 3 4 3 5% 6% 37%	2004
October	1st to 10th	Day	15% 6% 3 6% 4 4 3 3 5% 7% 45%	1900
	11th to 20th	Day	16% 5% 1 4 3 3 3 2 5% 5% 52%	1900
	21st to end	Day	13% 5% 2 5% 3 3 3 3 4 6% 53%	2090
November	1st to 10th	Day	13% 5% 2 4 3 4 3 3 4 5% 53%	1887
	11th to 20th	Day	15% 5% 1 6% 3 3 3 3 5% 7% 49%	1800
	21st to end	Day	14% 5% 2 5% 4 3 3 2 5% 4 52%	1645
December	1st to 10th	Day	11% 5% 2 5% 3 3 3 3 5% 6% 53%	2600
	11th to 20th	Day	19% 7% 3 5% 3 3 3 2 3 5% 47%	2990
	21st to end	Day	14% 6% 2 6% 4 4 4 3 5% 8% 44%	3960
January	1st to 10th	Night	14% 8% 3 6% 3 3 3 3 5% 6% 47%	4345
	11th to 20th	Night	17% 7% 2 6% 4 3 4 3 4 6% 45%	4120
	21st to end	Night	21% 9% 3 5% 4 3 3 2 4 4 43%	4532
February	1st to 10th	Night	15% 8% 2 5% 5% 4 4 4 5% 6% 42%	2470
	11th to 20th	Night	19% 8% 2 5% 4 4 3 3 5% 5% 43%	2314
	21st to end	Night	17% 6% 2 6% 4 3 3 4 5% 6% 45%	1884
March	1st to 10th	Night	24% 7% 2 6% 4 4 3 3 4 6% 37%	3460
	11th to 20th	Night	15% 5% 2 4 3 3 3 3 5% 6% 50%	3480
	21st to end	Night	16% 7% 3 6% 3 2 3 3 3 5% 49%	3754
April	1st to 10th	Night	14% 7% 2 6% 4 4 4 2 4 7% 45%	1900
	11th to 20th	Night	12% 5% 2 5% 4 4 4 3 5% 7% 49%	1875
	21st to end	Night	16% 6% 2 6% 4 4 4 4 5% 8% 43%	1900
May	1st to 10th	Night	19% 8% 2 7% 4 3 4 4 5% 8% 34%	3010
	11th to 20th	Night	21% 7% 3 6% 4 4 4 4 5% 6% 36%	2686
	21st to end	Night	10% 5% 2 6% 4 5% 5% 5% 7% 10% 43%	2732
June	1st to 10th	Night	10% 6% 2 6% 5% 5% 6% 5% 5% 9% 41%	1520
	11th to 20th	Night	9% 7% 2 5% 5% 4 5% 5% 8% 9% 41%	1520
	21st to end	Night	7% 6% 2 5% 4 4 5% 6% 6% 11% 43%	1520
July	1st to 10th	Night	7% 5% 2 6% 6% 5% 6% 5% 8% 10% 40%	2520
	11th to 20th	Night	10% 5% 2 7% 4 5% 5% 5% 8% 11% 37%	2766
	21st to end	Night	12% 7% 3 9% 6% 5% 6% 5% 7% 7% 31%	3087
August	1st to 10th	Night	16% 7% 3 8% 4 4 5% 4 7% 9% 31%	2825
	11th to 20th	Night	11% 7% 2 7% 5% 4 5% 5% 7% 9% 39%	2993
	21st to end	Night	9% 5% 2 5% 4 3 4 3 5% 8% 50%	3476
September	1st to 10th	Night	13% 6% 2 6% 4 4 5% 3 7% 8% 43%	1900
	11th to 20th	Night	11% 7% 2 6% 4 4 4 3 6% 7% 47%	1900
	21st to end	Night	20% 8% 3 6% 4 4 3 3 5% 6% 37%	2171
October	1st to 10th	Night	14% 7% 2 5% 3 4 4 3 5% 6% 47%	2280
	11th to 20th	Night	16% 5% 2 5% 3 3 2 3 4 5% 50%	2280
	21st to end	Night	14% 5% 2 5% 4 3 3 2 4 6% 52%	2508
November	1st to 10th	Night	12% 7% 2 5% 4 3 3 3 3 6% 51%	2410
	11th to 20th	Night	17% 7% 2 4 3 3 4 4 4 5% 48%	2600
	21st to end	Night	12% 5% 1 5% 3 3 4 3 6% 7% 51%	2750
December	1st to 10th	Night	10% 5% 2 4 3 3 3 3 5% 7% 55%	4580
	11th to 20th	Night	20% 7% 3 6% 3 4 4 3 5% 6% 40%	5205
	21st to end	Night	14% 7% 2 6% 3 4 3 3 5% 7% 45%	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	36% 4 7% 32% 17% 4	2732
	11th to 20th	Day	41% 4 8% 21% 20% 5%	2840
	21st to end	Day	47% 6% 8% 21% 15% 3	3124
February	1st to 10th	Day	43% 6% 9% 26% 13% 3	1710
	11th to 20th	Day	41% 5% 8% 22% 20% 4	1760
	21st to end	Day	48% 5% 10% 17% 16% 4	1570
March	1st to 10th	Day	49% 4 9% 17% 15% 5%	3391
	11th to 20th	Day	28% 5% 9% 26% 24% 8%	3480
	21st to end	Day	45% 5% 11% 18% 17% 3	3878
April	1st to 10th	Day	33% 6% 11% 23% 20% 8%	2280
	11th to 20th	Day	35% 4 11% 21% 22% 6%	2254
	21st to end	Day	40% 6% 11% 22% 15% 6%	2280
May	1st to 10th	Day	48% 8% 14% 19% 10% 2	3949
	11th to 20th	Day	46% 8% 13% 22% 9% 1	4207
	21st to end	Day	31% 9% 15% 24% 18% 3	4837
June	1st to 10th	Day	35% 8% 16% 25% 14% 2	2660
	11th to 20th	Day	36% 9% 15% 24% 16% 1	2660
	21st to end	Day	37% 8% 14% 23% 17% 2	2660
July	1st to 10th	Day	33% 8% 25% 18% 12% 4	4370
	11th to 20th	Day	43% 6% 23% 21% 7% 1	4118
	21st to end	Day	45% 7% 14% 17% 16% 1	4324
August	1st to 10th	Day	49% 7% 16% 21% 6% 1	4091
	11th to 20th	Day	41% 5% 14% 24% 15%	3840
	21st to end	Day	32% 5% 15% 27% 19% 2	4180
September	1st to 10th	Day	39% 8% 13% 16% 21% 4	2280
	11th to 20th	Day	39% 6% 9% 23% 20% 3	2280
	21st to end	Day	48% 6% 8% 20% 14% 4	2004
October	1st to 10th	Day	39% 3 7% 19% 27% 5%	3160
	11th to 20th	Day	27% 2 5% 20% 36% 11%	3140
	21st to end	Day	22% 2 9% 29% 27% 12%	3428
November	1st to 10th	Day	34% 5% 8% 27% 22% 4	1887
	11th to 20th	Day	36% 3 9% 22% 22% 7%	1800
	21st to end	Day	35% 3 8% 27% 22% 4	1645
December	1st to 10th	Day	33% 2 8% 30% 19% 7%	2600
	11th to 20th	Day	42% 2 12% 24% 16% 4	2986
	21st to end	Day	38% 4 12% 28% 17% 1	3960
January	1st to 10th	Night	38% 3 9% 25% 20% 6%	4345
	11th to 20th	Night	41% 5% 7% 23% 21% 4	4120
	21st to end	Night	45% 4 6% 24% 17% 4	4532
February	1st to 10th	Night	41% 6% 10% 24% 16% 2	2470
	11th to 20th	Night	43% 4 8% 20% 19% 6%	2316
	21st to end	Night	41% 4 9% 22% 17% 7%	1884
March	1st to 10th	Night	49% 3 8% 20% 17% 2	3460
	11th to 20th	Night	34% 5% 7% 22% 25% 7%	3480
	21st to end	Night	39% 4 8% 23% 21% 5%	3754
April	1st to 10th	Night	40% 5% 9% 17% 23% 6%	1900
	11th to 20th	Night	34% 6% 11% 22% 22% 6%	1875
	21st to end	Night	40% 6% 11% 22% 16% 5%	1900
May	1st to 10th	Night	48% 7% 14% 20% 10% 2	3040
	11th to 20th	Night	46% 9% 10% 24% 9% 1	2687
	21st to end	Night	33% 9% 17% 24% 15% 1	2739
June	1st to 10th	Night	38% 9% 13% 23% 15% 1	1520
	11th to 20th	Night	36% 11% 14% 23% 15% 1	1520
	21st to end	Night	33% 9% 15% 23% 17% 3	1520
July	1st to 10th	Night	38% 11% 18% 19% 11% 3	2480
	11th to 20th	Night	39% 8% 24% 22% 6% 1	2715
	21st to end	Night	50% 8% 13% 16% 13%	2988
August	1st to 10th	Night	48% 7% 16% 22% 7%	2814
	11th to 20th	Night	41% 6% 18% 23% 12%	3021
	21st to end	Night	32% 6% 11% 26% 24% 1	3476
September	1st to 10th	Night	36% 10% 15% 17% 16% 5%	1900
	11th to 20th	Night	36% 6% 11% 24% 21% 2	1900
	21st to end	Night	48% 6% 9% 17% 17% 3	2171
October	1st to 10th	Night	39% 3 10% 20% 22% 6%	3800
	11th to 20th	Night	25% 2 7% 22% 30% 13%	3779
	21st to end	Night	22% 2 5% 32% 27% 12%	4120
November	1st to 10th	Night	36% 4 9% 23% 22% 5%	2410
	11th to 20th	Night	38% 4 8% 20% 20% 9%	2600
	21st to end	Night	33% 4 9% 26% 23% 5%	2750
December	1st to 10th	Night	30% 3 9% 28% 26% 4	4580
	11th to 20th	Night	47% 3 11% 20% 14% 5%	5208
	21st to end	Night	38% 4 12% 29% 16% 1	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% 23% 32% 13% 4 1	241
	11th to 20th	Day	26% 32% 29% 11% 2	270
	21st to end	Day	25% 27% 36% 10% 2	297
February	1st to 10th	Day	22% 25% 39% 11% 3	270
	11th to 20th	Day	33% 24% 28% 15% 1	358
	21st to end	Day	32% 19% 30% 15% 4	382
March	1st to 10th	Day	23% 23% 33% 15% 5%	460
	11th to 20th	Day	24% 25% 31% 15% 5% 1	460
	21st to end	Day	24% 18% 38% 15% 5% 1	506
April	1st to 10th	Day	22% 23% 33% 16% 6%	460
	11th to 20th	Day	18% 16% 35% 20% 8% 3	452
	21st to end	Day	22% 16% 35% 19% 6% 2	460
May	1st to 10th	Day	21% 15% 32% 22% 8% 2	463
	11th to 20th	Day	20% 11% 32% 24% 11% 2	487
	21st to end	Day	19% 6% 26% 28% 16% 5%	529
June	1st to 10th	Day	13% 9% 29% 29% 16% 4	490
	11th to 20th	Day	12% 8% 26% 31% 17% 6%	490
	21st to end	Day	9% 9% 28% 32% 19% 3	490
July	1st to 10th	Day	11% 4 20% 34% 25% 7%	485
	11th to 20th	Day	7% 2 17% 40% 25% 8%	484
	21st to end	Day	11% 2 23% 34% 22% 8%	532
August	1st to 10th	Day	14% 3 19% 31% 26% 7%	486
	11th to 20th	Day	10% 4 19% 33% 23% 10%	479
	21st to end	Day	9% 4 19% 30% 22% 16%	539
September	1st to 10th	Day	13% 4 22% 28% 19% 13%	490
	11th to 20th	Day	13% 6% 22% 29% 20% 11%	490
	21st to end	Day	29% 9% 23% 24% 11% 5%	490
October	1st to 10th	Day	21% 7% 23% 24% 16% 8%	490
	11th to 20th	Day	17% 12% 27% 25% 17% 2	490
	21st to end	Day	16% 11% 37% 21% 10% 4	539
November	1st to 10th	Day	17% 13% 30% 24% 13% 3	460
	11th to 20th	Day	19% 15% 32% 24% 10% 1	400
	21st to end	Day	19% 16% 35% 20% 8% 2	245
December	1st to 10th	Day	21% 22% 38% 14% 5% 2	200
	11th to 20th	Day	23% 16% 34% 20% 8%	200
	21st to end	Day	21% 19% 32% 19% 7% 2	220
January	1st to 10th	Night	20% 20% 38% 18% 4	785
	11th to 20th	Night	21% 18% 32% 24% 4	760
	21st to end	Night	20% 18% 37% 23% 2	836
February	1st to 10th	Night	20% 15% 38% 24% 3	760
	11th to 20th	Night	25% 23% 33% 17% 2	743
	21st to end	Night	22% 20% 34% 20% 4	628
March	1st to 10th	Night	19% 18% 37% 23% 3	760
	11th to 20th	Night	23% 18% 34% 18% 5% 1	760
	21st to end	Night	19% 17% 39% 21% 4	836
April	1st to 10th	Night	18% 19% 39% 22% 3	760
	11th to 20th	Night	15% 14% 37% 26% 7%	751
	21st to end	Night	20% 10% 35% 29% 6%	760
May	1st to 10th	Night	18% 11% 35% 27% 8% 1	692
	11th to 20th	Night	18% 7% 31% 34% 9% 1	487
	21st to end	Night	15% 4 21% 38% 19% 2	411
June	1st to 10th	Night	12% 4 20% 43% 21% 1	380
	11th to 20th	Night	13% 4 22% 42% 17% 2	380
	21st to end	Night	9% 4 22% 45% 18% 2	380
July	1st to 10th	Night	11% 2 18% 37% 29% 2	370
	11th to 20th	Night	7% 2 13% 40% 33% 5%	507
	21st to end	Night	8% 4 19% 42% 25% 3	624
August	1st to 10th	Night	11% 3 16% 40% 28% 4	567
	11th to 20th	Night	13% 3 14% 41% 25% 4	682
	21st to end	Night	11% 3 14% 37% 30% 5%	836
September	1st to 10th	Night	16% 2 15% 37% 26% 4	760
	11th to 20th	Night	14% 3 16% 36% 26% 4	760
	21st to end	Night	25% 5% 21% 29% 18% 2	760
October	1st to 10th	Night	17% 5% 23% 30% 22% 4	760
	11th to 20th	Night	19% 8% 27% 30% 16% 1	760
	21st to end	Night	16% 11% 31% 27% 15% 1	836
November	1st to 10th	Night	15% 9% 30% 31% 12% 3	780
	11th to 20th	Night	20% 13% 30% 29% 8%	800
	21st to end	Night	14% 14% 33% 28% 9% 1	800
December	1st to 10th	Night	23% 13% 34% 21% 8% 1	800
	11th to 20th	Night	19% 12% 36% 27% 6%	800
	21st to end	Night	19% 16% 28% 32% 5%	880

Page generated at 2025-01-04 03:23:58. Version ac07

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