Hutville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hutville clear sky chart from 2005-11-06 to 2024-11-05.

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% 10% 4 8% 5% 5% 5% 4 6% 7% 32%	101434
	Night	14% 10% 4 8% 5% 4 4 4 5% 7% 35%	97528
Transparency	Day	48% 6% 11% 21% 12% 2	105127
	Night	47% 6% 11% 21% 13% 2	101974
Seeing	Day	19% 12% 26% 22% 15% 6%	15057
	Night	18% 9% 28% 29% 14% 2	24932

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% 18% 8% 13% 5% 4 4 3 5% 5% 17%	2836
	11th to 20th	Day	14% 20% 8% 12% 6% 8% 7% 3 4 4 15%	2840
	21st to end	Day	25% 20% 11% 10% 6% 5% 3 2 4 3 11%	3124
February	1st to 10th	Day	19% 15% 6% 10% 7% 6% 3 3 4 4 24%	1710
	11th to 20th	Day	15% 13% 5% 15% 7% 4 4 3 5% 6% 24%	1800
	21st to end	Day	17% 17% 4 10% 6% 3 3 2 4 7% 27%	1570
March	1st to 10th	Day	21% 14% 6% 10% 5% 4 4 3 5% 6% 22%	3294
	11th to 20th	Day	13% 10% 4 8% 5% 5% 5% 4 5% 6% 37%	3480
	21st to end	Day	20% 9% 3 8% 4 5% 4 3 5% 6% 32%	3815
April	1st to 10th	Day	14% 13% 3 8% 6% 4 5% 3 5% 7% 32%	2115
	11th to 20th	Day	16% 11% 3 7% 5% 5% 3 3 4 6% 36%	2417
	21st to end	Day	18% 9% 3 8% 5% 6% 4 4 6% 6% 32%	2470
May	1st to 10th	Day	21% 10% 3 7% 6% 5% 4 4 5% 6% 29%	4082
	11th to 20th	Day	20% 8% 2 8% 4 4 4 3 5% 7% 34%	4081
	21st to end	Day	11% 7% 2 7% 5% 5% 6% 5% 7% 9% 35%	4476
June	1st to 10th	Day	11% 6% 2 7% 6% 5% 5% 5% 7% 8% 37%	2470
	11th to 20th	Day	11% 6% 3 7% 5% 5% 5% 4 7% 9% 38%	2470
	21st to end	Day	11% 6% 2 6% 5% 6% 5% 5% 8% 10% 36%	2610
July	1st to 10th	Day	10% 6% 3 7% 6% 5% 6% 4 7% 9% 38%	4198
	11th to 20th	Day	8% 5% 2 6% 4 5% 5% 5% 8% 11% 42%	4120
	21st to end	Day	10% 7% 3 7% 5% 6% 6% 4 7% 9% 36%	4466
August	1st to 10th	Day	8% 6% 3 7% 5% 5% 5% 5% 7% 10% 38%	4104
	11th to 20th	Day	8% 7% 2 7% 5% 6% 6% 6% 9% 10% 36%	4044
	21st to end	Day	6% 4 2 6% 5% 5% 7% 5% 7% 10% 43%	4491
September	1st to 10th	Day	12% 6% 2 5% 4 4 4 4 5% 7% 47%	2090
	11th to 20th	Day	9% 6% 2 6% 4 4 5% 3 5% 9% 46%	2090
	21st to end	Day	19% 7% 2 6% 4 4 4 3 4 5% 42%	2090
October	1st to 10th	Day	13% 6% 3 6% 5% 4 4 4 5% 8% 43%	2019
	11th to 20th	Day	14% 8% 2 6% 4 4 4 3 6% 7% 41%	1900
	21st to end	Day	19% 10% 2 8% 4 4 4 3 5% 7% 33%	2047
November	1st to 10th	Day	10% 9% 2 5% 4 3 6% 4 5% 7% 46%	1708
	11th to 20th	Day	16% 11% 5% 7% 6% 4 3 3 5% 5% 34%	1710
	21st to end	Day	17% 14% 5% 8% 6% 5% 3 3 4 6% 29%	1710
December	1st to 10th	Day	18% 18% 7% 11% 6% 4 4 3 5% 5% 19%	1710
	11th to 20th	Day	17% 15% 6% 13% 6% 4 4 3 5% 5% 21%	2153
	21st to end	Day	23% 23% 7% 11% 5% 4 4 3 4 5% 11%	3124
January	1st to 10th	Night	14% 20% 8% 13% 6% 5% 4 3 4 4 19%	4109
	11th to 20th	Night	15% 16% 8% 16% 7% 5% 6% 4 4 4 15%	4120
	21st to end	Night	24% 18% 8% 12% 6% 4 3 2 3 4 15%	4532
February	1st to 10th	Night	19% 14% 4 10% 6% 5% 4 3 5% 5% 26%	2470
	11th to 20th	Night	16% 12% 4 10% 7% 4 6% 3 6% 6% 26%	2263
	21st to end	Night	18% 14% 4 11% 6% 5% 3 3 4 6% 26%	1884
March	1st to 10th	Night	20% 13% 5% 6% 4 4 4 3 5% 5% 31%	3557
	11th to 20th	Night	13% 8% 3 8% 5% 4 4 3 5% 6% 40%	3480
	21st to end	Night	18% 10% 3 7% 4 4 4 3 4 6% 38%	3817
April	1st to 10th	Night	15% 10% 3 6% 5% 4 5% 4 5% 8% 36%	2081
	11th to 20th	Night	14% 9% 3 7% 6% 5% 4 4 6% 6% 37%	1711
	21st to end	Night	14% 9% 2 8% 5% 4 4 4 5% 7% 37%	1710
May	1st to 10th	Night	24% 11% 3 7% 4 4 5% 4 5% 6% 27%	2813
	11th to 20th	Night	17% 8% 3 6% 4 3 3 3 5% 9% 39%	2812
	21st to end	Night	9% 5% 2 6% 4 4 5% 4 8% 10% 43%	3079
June	1st to 10th	Night	8% 6% 3 6% 5% 4 4 4 6% 8% 45%	1710
	11th to 20th	Night	8% 5% 2 6% 4 4 5% 4 8% 11% 43%	1710
	21st to end	Night	9% 5% 2 5% 5% 5% 5% 5% 7% 10% 44%	1552
July	1st to 10th	Night	11% 6% 2 6% 4 4 5% 4 6% 7% 45%	2737
	11th to 20th	Night	8% 4 2 5% 5% 4 5% 5% 7% 10% 47%	2840
	21st to end	Night	7% 6% 2 8% 5% 5% 5% 5% 7% 9% 42%	3087
August	1st to 10th	Night	8% 6% 3 8% 5% 5% 5% 5% 7% 9% 38%	2825
	11th to 20th	Night	8% 9% 3 8% 5% 4 4 3 5% 7% 44%	2785
	21st to end	Night	4 4 2 4 4 5% 5% 5% 7% 8% 50%	3144
September	1st to 10th	Night	11% 5% 2 5% 3 4 4 3 5% 8% 51%	2076
	11th to 20th	Night	8% 5% 2 5% 3 3 3 3 5% 8% 56%	2090
	21st to end	Night	15% 6% 2 6% 4 3 4 4 5% 5% 46%	2090
October	1st to 10th	Night	10% 5% 2 6% 4 4 3 3 6% 7% 49%	2161
	11th to 20th	Night	14% 9% 2 7% 3 5% 4 4 5% 6% 42%	2280
	21st to end	Night	20% 8% 2 7% 4 4 5% 4 4 6% 37%	2549
November	1st to 10th	Night	12% 8% 2 6% 4 3 4 3 5% 6% 46%	2470
	11th to 20th	Night	16% 10% 4 9% 5% 4 4 4 4 7% 34%	2470
	21st to end	Night	18% 13% 3 8% 6% 4 4 4 5% 6% 29%	2470
December	1st to 10th	Night	19% 15% 6% 11% 5% 5% 4 3 5% 5% 22%	2470
	11th to 20th	Night	16% 13% 6% 10% 6% 4 4 4 5% 6% 26%	3042
	21st to end	Night	22% 20% 7% 11% 5% 4 4 3 4 5% 15%	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	69% 4 8% 13% 5%	2837
	11th to 20th	Day	74% 3 10% 10% 3	2840
	21st to end	Day	80% 4 6% 7% 3	3124
February	1st to 10th	Day	64% 5% 9% 14% 7% 1	1710
	11th to 20th	Day	62% 5% 8% 16% 8% 1	1810
	21st to end	Day	59% 4 10% 19% 6% 2	1570
March	1st to 10th	Day	63% 5% 9% 19% 4	3294
	11th to 20th	Day	47% 6% 10% 26% 10% 1	3480
	21st to end	Day	52% 6% 10% 22% 10%	3815
April	1st to 10th	Day	52% 5% 13% 17% 11% 2	2115
	11th to 20th	Day	49% 5% 11% 18% 13% 3	2417
	21st to end	Day	51% 6% 10% 20% 11% 2	2470
May	1st to 10th	Day	54% 7% 12% 20% 7% 1	4120
	11th to 20th	Day	49% 6% 13% 21% 10% 1	4085
	21st to end	Day	39% 10% 14% 21% 12% 4	4489
June	1st to 10th	Day	42% 7% 11% 25% 14% 1	2470
	11th to 20th	Day	41% 9% 14% 21% 14% 1	2470
	21st to end	Day	40% 10% 14% 20% 14% 2	2610
July	1st to 10th	Day	41% 8% 11% 22% 15% 3	4133
	11th to 20th	Day	32% 8% 14% 27% 18% 1	4051
	21st to end	Day	41% 8% 13% 18% 18% 3	4324
August	1st to 10th	Day	38% 9% 15% 25% 12%	4091
	11th to 20th	Day	37% 9% 12% 27% 14% 1	4083
	21st to end	Day	32% 8% 15% 29% 12% 3	4491
September	1st to 10th	Day	36% 7% 11% 22% 21% 4	2090
	11th to 20th	Day	35% 6% 12% 25% 19% 3	2090
	21st to end	Day	44% 4 9% 22% 19% 1	2090
October	1st to 10th	Day	27% 5% 10% 33% 24% 1	3357
	11th to 20th	Day	35% 6% 10% 26% 19% 4	3140
	21st to end	Day	39% 4 12% 25% 18% 2	3349
November	1st to 10th	Day	38% 5% 11% 26% 17% 3	1708
	11th to 20th	Day	52% 5% 9% 21% 11% 3	1710
	21st to end	Day	57% 4 10% 19% 9% 1	1710
December	1st to 10th	Day	67% 5% 9% 15% 3	1710
	11th to 20th	Day	65% 4 9% 17% 5%	2150
	21st to end	Day	76% 6% 8% 7% 3	3124
January	1st to 10th	Night	69% 4 8% 14% 5%	4109
	11th to 20th	Night	72% 5% 9% 10% 3	4120
	21st to end	Night	75% 3 6% 11% 3	4532
February	1st to 10th	Night	61% 4 11% 16% 8% 1	2470
	11th to 20th	Night	58% 4 10% 17% 9% 1	2264
	21st to end	Night	61% 4 9% 15% 9% 2	1884
March	1st to 10th	Night	54% 6% 9% 21% 9% 1	3557
	11th to 20th	Night	43% 6% 11% 29% 9% 2	3480
	21st to end	Night	48% 4 9% 27% 11% 1	3817
April	1st to 10th	Night	46% 6% 11% 21% 14% 2	2081
	11th to 20th	Night	44% 6% 12% 17% 18% 3	1711
	21st to end	Night	45% 7% 11% 20% 16% 2	1710
May	1st to 10th	Night	56% 7% 8% 19% 8% 2	2840
	11th to 20th	Night	44% 6% 11% 27% 11% 1	2813
	21st to end	Night	32% 9% 15% 27% 13% 3	3087
June	1st to 10th	Night	35% 9% 12% 23% 19% 2	1710
	11th to 20th	Night	33% 8% 14% 25% 17% 3	1710
	21st to end	Night	33% 10% 13% 24% 17% 3	1552
July	1st to 10th	Night	37% 7% 12% 22% 17% 5%	2692
	11th to 20th	Night	30% 8% 14% 30% 17% 1	2786
	21st to end	Night	36% 9% 14% 21% 17% 4	2988
August	1st to 10th	Night	39% 8% 15% 24% 12% 1	2814
	11th to 20th	Night	39% 7% 10% 25% 19% 1	2812
	21st to end	Night	27% 9% 16% 29% 17% 2	3144
September	1st to 10th	Night	32% 6% 12% 24% 20% 6%	2076
	11th to 20th	Night	27% 5% 11% 27% 26% 3	2090
	21st to end	Night	39% 5% 10% 21% 23% 1	2090
October	1st to 10th	Night	27% 4 7% 29% 31% 2	3603
	11th to 20th	Night	31% 4 11% 28% 21% 5%	3779
	21st to end	Night	35% 4 8% 27% 22% 4	4197
November	1st to 10th	Night	38% 5% 12% 23% 19% 3	2470
	11th to 20th	Night	50% 4 8% 21% 14% 2	2470
	21st to end	Night	55% 4 12% 20% 7% 1	2470
December	1st to 10th	Night	63% 6% 9% 17% 5%	2470
	11th to 20th	Night	58% 5% 12% 19% 6%	3044
	21st to end	Night	73% 5% 9% 11% 3	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	26% 21% 35% 12% 6% 1	270
	11th to 20th	Day	28% 20% 41% 10% 1 1	270
	21st to end	Day	29% 23% 31% 14% 3	297
February	1st to 10th	Day	28% 24% 32% 13% 1 1	270
	11th to 20th	Day	29% 26% 32% 10% 2	270
	21st to end	Day	30% 28% 31% 10% 1	225
March	1st to 10th	Day	23% 22% 33% 18% 4	366
	11th to 20th	Day	27% 15% 34% 19% 5%	460
	21st to end	Day	29% 16% 32% 19% 4 1	506
April	1st to 10th	Day	22% 17% 33% 17% 9% 2	460
	11th to 20th	Day	25% 17% 28% 16% 10% 4	452
	21st to end	Day	24% 15% 32% 20% 7% 2	460
May	1st to 10th	Day	26% 12% 30% 19% 10% 3	463
	11th to 20th	Day	22% 9% 25% 25% 14% 5%	487
	21st to end	Day	13% 7% 22% 29% 19% 9%	529
June	1st to 10th	Day	12% 6% 25% 33% 18% 6%	490
	11th to 20th	Day	14% 8% 21% 29% 22% 6%	490
	21st to end	Day	13% 7% 27% 29% 18% 6%	630
July	1st to 10th	Day	13% 3 18% 25% 23% 19%	537
	11th to 20th	Day	10% 5% 22% 26% 25% 12%	484
	21st to end	Day	11% 3 19% 29% 26% 12%	532
August	1st to 10th	Day	11% 5% 15% 25% 29% 16%	486
	11th to 20th	Day	12% 5% 20% 28% 23% 11%	479
	21st to end	Day	7% 3 16% 29% 29% 15%	539
September	1st to 10th	Day	12% 4 17% 26% 27% 13%	490
	11th to 20th	Day	11% 2 15% 24% 33% 15%	490
	21st to end	Day	23% 8% 19% 24% 18% 8%	490
October	1st to 10th	Day	11% 8% 25% 28% 20% 7%	490
	11th to 20th	Day	15% 15% 31% 23% 12% 3	490
	21st to end	Day	25% 13% 32% 21% 8% 1	496
November	1st to 10th	Day	15% 15% 36% 20% 12% 2	282
	11th to 20th	Day	23% 19% 30% 17% 9% 2	270
	21st to end	Day	26% 19% 36% 16% 3	270
December	1st to 10th	Day	25% 21% 33% 16% 4 2	270
	11th to 20th	Day	22% 21% 41% 12% 3	270
	21st to end	Day	32% 19% 31% 15% 3	297
January	1st to 10th	Night	24% 17% 37% 19% 4	760
	11th to 20th	Night	27% 16% 34% 19% 3	760
	21st to end	Night	24% 14% 35% 23% 3	836
February	1st to 10th	Night	26% 13% 35% 24% 2	760
	11th to 20th	Night	23% 17% 37% 21% 2	743
	21st to end	Night	26% 14% 39% 19% 2	628
March	1st to 10th	Night	21% 12% 35% 26% 5%	760
	11th to 20th	Night	19% 15% 33% 25% 7%	760
	21st to end	Night	22% 13% 32% 27% 6% 1	836
April	1st to 10th	Night	18% 13% 36% 26% 6% 1	751
	11th to 20th	Night	16% 13% 34% 25% 10% 2	563
	21st to end	Night	19% 6% 39% 27% 8% 1	570
May	1st to 10th	Night	20% 9% 29% 29% 13% 1	570
	11th to 20th	Night	20% 4 26% 35% 13% 2	561
	21st to end	Night	9% 3 22% 37% 26% 3	617
June	1st to 10th	Night	9% 3 23% 41% 23% 1	570
	11th to 20th	Night	10% 4 18% 43% 24% 2	570
	21st to end	Night	11% 2 23% 40% 22% 3	570
July	1st to 10th	Night	11% 2 14% 40% 26% 8%	555
	11th to 20th	Night	8% 1 15% 39% 32% 5%	552
	21st to end	Night	10% 2 13% 40% 33% 3	624
August	1st to 10th	Night	8% 2 10% 43% 32% 5%	567
	11th to 20th	Night	10% 2 14% 38% 31% 4	564
	21st to end	Night	7% 2 12% 37% 34% 8%	627
September	1st to 10th	Night	13% 3 15% 33% 30% 6%	746
	11th to 20th	Night	10% 2 13% 38% 32% 6%	760
	21st to end	Night	17% 5% 22% 30% 23% 3	760
October	1st to 10th	Night	13% 6% 22% 35% 21% 4	760
	11th to 20th	Night	18% 9% 30% 28% 13% 1	760
	21st to end	Night	22% 10% 31% 27% 9%	836
November	1st to 10th	Night	16% 9% 29% 30% 15% 1	760
	11th to 20th	Night	21% 14% 30% 26% 8% 1	760
	21st to end	Night	23% 11% 33% 26% 7% 1	760
December	1st to 10th	Night	28% 12% 33% 23% 4	760
	11th to 20th	Night	24% 12% 36% 23% 5%	760
	21st to end	Night	29% 13% 32% 22% 3	836

Page generated at 2024-11-03 02:11:13. Version ac07

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