Seven Ponds
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Seven Ponds clear sky chart from 2005-11-06 to 2024-11-04.

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% 10% 3 8% 5% 5% 5% 4 6% 7% 33%	100996
	Night	14% 10% 4 8% 5% 4 4 4 5% 7% 35%	97973
Transparency	Day	46% 7% 13% 20% 12% 1	104609
	Night	46% 7% 12% 21% 12% 1	102500
Seeing	Day	16% 12% 30% 23% 13% 5%	15394
	Night	18% 11% 31% 29% 11% 1	25019

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% 19% 7% 12% 6% 5% 4 4 5% 5% 21%	2527
	11th to 20th	Day	14% 19% 6% 13% 9% 7% 5% 4 5% 6% 12%	2530
	21st to end	Day	25% 20% 6% 11% 6% 4 3 2 4 4 16%	3062
February	1st to 10th	Day	13% 14% 5% 12% 10% 7% 5% 4 4 6% 22%	1710
	11th to 20th	Day	12% 13% 6% 11% 8% 6% 5% 4 5% 6% 23%	1774
	21st to end	Day	13% 15% 4 13% 7% 4 4 4 4 6% 26%	1570
March	1st to 10th	Day	17% 15% 5% 10% 6% 4 4 3 4 5% 28%	3206
	11th to 20th	Day	11% 13% 5% 10% 7% 5% 5% 3 6% 6% 29%	3480
	21st to end	Day	17% 13% 3 9% 6% 4 5% 3 5% 5% 29%	3815
April	1st to 10th	Day	15% 13% 4 8% 6% 4 4 4 5% 6% 30%	2199
	11th to 20th	Day	16% 10% 3 7% 4 5% 5% 4 6% 6% 34%	2423
	21st to end	Day	16% 10% 3 8% 6% 5% 4 3 5% 7% 34%	2470
May	1st to 10th	Day	16% 9% 3 7% 5% 5% 5% 4 5% 7% 36%	4082
	11th to 20th	Day	16% 8% 2 7% 5% 5% 5% 4 7% 8% 34%	4081
	21st to end	Day	9% 6% 2 7% 4 4 4 4 5% 7% 46%	4476
June	1st to 10th	Day	9% 7% 2 7% 5% 4 5% 5% 7% 9% 40%	2826
	11th to 20th	Day	10% 5% 2 7% 5% 5% 5% 5% 7% 8% 42%	2850
	21st to end	Day	10% 7% 2 7% 5% 5% 6% 5% 7% 10% 37%	2799
July	1st to 10th	Day	10% 6% 2 7% 6% 5% 6% 6% 7% 9% 37%	4440
	11th to 20th	Day	7% 4 2 5% 4 5% 5% 5% 7% 10% 46%	4440
	21st to end	Day	7% 5% 2 7% 5% 6% 7% 5% 7% 9% 40%	4543
August	1st to 10th	Day	12% 5% 2 6% 4 5% 5% 4 7% 8% 40%	4104
	11th to 20th	Day	9% 6% 2 7% 5% 5% 5% 5% 7% 9% 40%	4044
	21st to end	Day	8% 6% 3 7% 5% 6% 6% 5% 7% 9% 38%	4518
September	1st to 10th	Day	10% 7% 2 7% 5% 6% 6% 5% 7% 8% 39%	2142
	11th to 20th	Day	10% 4 2 5% 4 3 5% 4 7% 10% 46%	2090
	21st to end	Day	15% 7% 2 7% 4 6% 5% 5% 7% 9% 33%	2090
October	1st to 10th	Day	13% 7% 2 6% 5% 5% 4 4 6% 6% 42%	2024
	11th to 20th	Day	17% 10% 3 7% 5% 5% 5% 4 4 6% 34%	1900
	21st to end	Day	18% 12% 4 8% 5% 5% 4 3 6% 7% 29%	1938
November	1st to 10th	Day	11% 9% 4 8% 5% 5% 5% 3 6% 8% 36%	1699
	11th to 20th	Day	13% 11% 4 9% 8% 6% 5% 4 6% 6% 30%	1710
	21st to end	Day	16% 14% 6% 7% 6% 5% 5% 3 5% 7% 27%	1549
December	1st to 10th	Day	12% 15% 7% 13% 8% 5% 5% 3 5% 6% 21%	1520
	11th to 20th	Day	15% 15% 5% 10% 5% 4 5% 4 6% 7% 24%	1742
	21st to end	Day	22% 21% 7% 12% 5% 5% 4 3 4 5% 12%	2623
January	1st to 10th	Night	16% 14% 7% 10% 6% 5% 5% 3 5% 6% 24%	4428
	11th to 20th	Night	12% 16% 7% 15% 7% 7% 6% 4 5% 5% 16%	4440
	21st to end	Night	21% 15% 9% 11% 6% 4 4 2 4 5% 19%	4592
February	1st to 10th	Night	13% 16% 5% 10% 8% 6% 6% 4 5% 5% 23%	2470
	11th to 20th	Night	12% 12% 4 11% 6% 5% 5% 4 6% 6% 27%	2291
	21st to end	Night	16% 12% 3 9% 6% 5% 5% 3 5% 6% 28%	1884
March	1st to 10th	Night	14% 14% 4 10% 4 4 4 2 4 6% 35%	3645
	11th to 20th	Night	9% 9% 3 7% 5% 5% 5% 4 6% 8% 41%	3480
	21st to end	Night	15% 9% 3 10% 5% 4 4 3 4 5% 38%	3817
April	1st to 10th	Night	16% 10% 3 7% 5% 4 4 4 5% 6% 34%	1995
	11th to 20th	Night	18% 7% 3 7% 5% 3 4 3 6% 7% 37%	1705
	21st to end	Night	17% 9% 2 5% 5% 4 4 4 6% 7% 38%	1710
May	1st to 10th	Night	16% 9% 3 6% 5% 4 4 4 6% 8% 36%	2813
	11th to 20th	Night	13% 7% 3 7% 5% 4 4 3 5% 7% 42%	2812
	21st to end	Night	9% 5% 3 6% 4 3 4 4 6% 7% 50%	3062
June	1st to 10th	Night	10% 5% 2 6% 4 3 5% 4 6% 8% 47%	1349
	11th to 20th	Night	9% 6% 2 6% 4 3 4 6% 7% 8% 45%	1330
	21st to end	Night	7% 7% 2 6% 4 5% 4 3 6% 8% 48%	1375
July	1st to 10th	Night	8% 5% 2 4 4 4 4 4 7% 11% 48%	2530
	11th to 20th	Night	9% 4 1 3 4 4 5% 3 6% 9% 53%	2530
	21st to end	Night	4 4 1 6% 5% 5% 6% 5% 8% 9% 47%	2996
August	1st to 10th	Night	10% 5% 3 6% 4 4 3 4 5% 8% 47%	2825
	11th to 20th	Night	9% 6% 2 6% 4 4 4 4 6% 8% 48%	2785
	21st to end	Night	8% 6% 2 7% 4 4 5% 3 5% 7% 48%	3124
September	1st to 10th	Night	10% 6% 2 6% 4 4 5% 4 6% 6% 48%	2017
	11th to 20th	Night	9% 5% 1 5% 3 2 4 3 5% 7% 54%	2090
	21st to end	Night	14% 7% 3 7% 5% 4 4 3 6% 6% 42%	2090
October	1st to 10th	Night	13% 6% 3 6% 4 4 4 4 5% 7% 44%	2155
	11th to 20th	Night	18% 8% 3 8% 4 4 5% 4 5% 6% 36%	2280
	21st to end	Night	20% 9% 4 7% 5% 5% 5% 3 5% 6% 31%	2655
November	1st to 10th	Night	13% 8% 3 6% 4 4 4 4 5% 7% 43%	2452
	11th to 20th	Night	15% 10% 3 7% 5% 5% 6% 5% 6% 7% 30%	2470
	21st to end	Night	17% 14% 4 8% 6% 4 5% 3 6% 7% 27%	2626
December	1st to 10th	Night	15% 16% 5% 11% 6% 5% 5% 4 5% 6% 21%	2660
	11th to 20th	Night	13% 13% 4 13% 7% 5% 5% 4 5% 6% 24%	3450
	21st to end	Night	24% 24% 6% 10% 5% 4 3 2 4 4 13%	5040

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	63% 9% 9% 13% 5% 1	2528
	11th to 20th	Day	71% 9% 12% 6% 3	2530
	21st to end	Day	74% 5% 11% 6% 3 1	3062
February	1st to 10th	Day	63% 7% 9% 14% 7%	1710
	11th to 20th	Day	60% 6% 10% 14% 9% 1	1783
	21st to end	Day	59% 7% 11% 15% 7% 2	1570
March	1st to 10th	Day	57% 7% 12% 18% 6%	3206
	11th to 20th	Day	52% 8% 12% 19% 7% 2	3480
	21st to end	Day	55% 7% 13% 13% 10% 2	3815
April	1st to 10th	Day	51% 8% 12% 18% 10% 1	2199
	11th to 20th	Day	47% 8% 12% 19% 13% 2	2423
	21st to end	Day	50% 6% 14% 17% 12% 1	2470
May	1st to 10th	Day	45% 8% 13% 21% 11% 2	4120
	11th to 20th	Day	43% 10% 15% 22% 9% 1	4085
	21st to end	Day	36% 7% 12% 18% 23% 5%	4489
June	1st to 10th	Day	38% 8% 14% 24% 14% 2	2826
	11th to 20th	Day	37% 8% 13% 24% 16% 2	2850
	21st to end	Day	39% 9% 13% 22% 15% 1	2799
July	1st to 10th	Day	40% 8% 16% 20% 15% 2	4371
	11th to 20th	Day	29% 8% 14% 33% 14% 1	4365
	21st to end	Day	37% 8% 15% 17% 21% 1	4399
August	1st to 10th	Day	38% 9% 14% 22% 16% 1	4091
	11th to 20th	Day	38% 9% 12% 29% 11% 1	4083
	21st to end	Day	39% 7% 14% 28% 12% 1	4517
September	1st to 10th	Day	39% 9% 15% 24% 12% 2	2142
	11th to 20th	Day	33% 7% 15% 30% 14% 1	2090
	21st to end	Day	45% 7% 15% 22% 11% 1	2090
October	1st to 10th	Day	32% 6% 11% 31% 19% 2	3362
	11th to 20th	Day	41% 5% 12% 24% 17%	3140
	21st to end	Day	46% 6% 13% 23% 11% 1	3175
November	1st to 10th	Day	45% 8% 13% 23% 10% 1	1699
	11th to 20th	Day	53% 7% 13% 17% 9% 1	1710
	21st to end	Day	56% 7% 14% 17% 6% 1	1549
December	1st to 10th	Day	63% 8% 12% 13% 4	1520
	11th to 20th	Day	57% 9% 14% 14% 6%	1738
	21st to end	Day	75% 6% 10% 6% 3	2623
January	1st to 10th	Night	58% 8% 13% 15% 5% 1	4428
	11th to 20th	Night	67% 10% 10% 10% 3	4440
	21st to end	Night	69% 5% 9% 14% 3	4592
February	1st to 10th	Night	61% 8% 10% 13% 7% 1	2470
	11th to 20th	Night	55% 8% 10% 18% 9% 1	2293
	21st to end	Night	54% 7% 12% 17% 8% 1	1884
March	1st to 10th	Night	49% 6% 14% 23% 6% 1	3645
	11th to 20th	Night	39% 8% 15% 21% 15% 1	3480
	21st to end	Night	47% 7% 12% 22% 11% 1	3817
April	1st to 10th	Night	49% 5% 11% 20% 12% 2	1995
	11th to 20th	Night	44% 7% 11% 18% 17% 2	1705
	21st to end	Night	43% 6% 12% 19% 16% 3	1710
May	1st to 10th	Night	43% 8% 12% 21% 13% 4	2840
	11th to 20th	Night	40% 7% 12% 27% 12% 2	2813
	21st to end	Night	31% 8% 12% 22% 20% 7%	3070
June	1st to 10th	Night	34% 7% 12% 28% 17% 2	1349
	11th to 20th	Night	33% 9% 14% 23% 19% 2	1330
	21st to end	Night	34% 6% 12% 27% 20% 1	1375
July	1st to 10th	Night	28% 7% 15% 28% 16% 6%	2490
	11th to 20th	Night	28% 6% 14% 32% 19% 1	2482
	21st to end	Night	29% 11% 18% 20% 21% 2	2900
August	1st to 10th	Night	34% 7% 15% 28% 15% 1	2814
	11th to 20th	Night	32% 8% 15% 31% 12% 2	2812
	21st to end	Night	34% 8% 12% 31% 15% 1	3124
September	1st to 10th	Night	35% 7% 14% 27% 16% 2	2017
	11th to 20th	Night	29% 7% 14% 30% 19% 2	2090
	21st to end	Night	40% 7% 11% 29% 12% 1	2090
October	1st to 10th	Night	27% 4 12% 31% 25% 1	3597
	11th to 20th	Night	43% 6% 11% 23% 17%	3779
	21st to end	Night	43% 5% 12% 28% 11% 1	4368
November	1st to 10th	Night	40% 7% 13% 26% 13% 1	2452
	11th to 20th	Night	51% 8% 13% 19% 8% 1	2470
	21st to end	Night	56% 6% 15% 17% 6%	2626
December	1st to 10th	Night	62% 7% 12% 15% 4	2660
	11th to 20th	Night	57% 9% 12% 15% 6%	3453
	21st to end	Night	74% 6% 10% 7% 3	5040

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	20% 21% 37% 14% 7%	270
	11th to 20th	Day	20% 19% 44% 13% 4 1	270
	21st to end	Day	27% 16% 36% 17% 4 1	297
February	1st to 10th	Day	21% 22% 39% 14% 3 1	270
	11th to 20th	Day	22% 21% 38% 16% 2	270
	21st to end	Day	20% 32% 35% 11% 2	225
March	1st to 10th	Day	26% 20% 36% 15% 3 1	317
	11th to 20th	Day	18% 16% 36% 22% 7% 1	460
	21st to end	Day	26% 14% 33% 21% 5% 1	506
April	1st to 10th	Day	16% 19% 36% 20% 8% 1	460
	11th to 20th	Day	25% 16% 31% 14% 9% 4	452
	21st to end	Day	23% 13% 28% 23% 9% 2	460
May	1st to 10th	Day	21% 14% 28% 24% 11% 3	463
	11th to 20th	Day	18% 10% 32% 21% 14% 6%	487
	21st to end	Day	15% 8% 24% 27% 17% 9%	529
June	1st to 10th	Day	12% 9% 32% 30% 13% 4	680
	11th to 20th	Day	12% 9% 29% 31% 15% 4	680
	21st to end	Day	11% 10% 29% 31% 15% 5%	680
July	1st to 10th	Day	8% 6% 22% 31% 21% 11%	671
	11th to 20th	Day	9% 7% 27% 29% 20% 8%	668
	21st to end	Day	7% 5% 24% 31% 23% 10%	583
August	1st to 10th	Day	10% 5% 21% 25% 27% 13%	486
	11th to 20th	Day	9% 5% 20% 29% 25% 12%	479
	21st to end	Day	12% 6% 21% 28% 22% 12%	539
September	1st to 10th	Day	11% 7% 25% 25% 19% 12%	490
	11th to 20th	Day	10% 3 19% 25% 28% 14%	490
	21st to end	Day	17% 13% 23% 22% 19% 8%	490
October	1st to 10th	Day	17% 10% 28% 23% 14% 8%	490
	11th to 20th	Day	18% 16% 34% 22% 7% 1	490
	21st to end	Day	24% 17% 35% 18% 5% 1	387
November	1st to 10th	Day	14% 21% 35% 20% 8% 1	279
	11th to 20th	Day	19% 22% 35% 17% 6% 1	270
	21st to end	Day	23% 22% 39% 13% 4	194
December	1st to 10th	Day	20% 22% 37% 13% 7% 1	180
	11th to 20th	Day	23% 26% 36% 12% 3 1	180
	21st to end	Day	25% 21% 38% 13% 3	252
January	1st to 10th	Night	20% 14% 40% 20% 5% 1	950
	11th to 20th	Night	23% 17% 35% 21% 3 1	950
	21st to end	Night	18% 13% 37% 26% 5%	870
February	1st to 10th	Night	21% 16% 39% 21% 3	760
	11th to 20th	Night	20% 18% 35% 23% 5%	743
	21st to end	Night	22% 18% 38% 20% 2	628
March	1st to 10th	Night	20% 13% 37% 25% 5%	760
	11th to 20th	Night	17% 15% 37% 25% 6% 1	760
	21st to end	Night	22% 12% 33% 27% 6% 1	836
April	1st to 10th	Night	21% 15% 35% 26% 4	665
	11th to 20th	Night	21% 11% 35% 23% 7% 2	563
	21st to end	Night	18% 9% 32% 32% 7%	570
May	1st to 10th	Night	16% 8% 34% 33% 9% 1	570
	11th to 20th	Night	19% 5% 30% 33% 13% 1	561
	21st to end	Night	10% 4 26% 40% 18% 2	617
June	1st to 10th	Night	11% 5% 27% 45% 11%	399
	11th to 20th	Night	11% 6% 30% 42% 12%	380
	21st to end	Night	9% 6% 23% 46% 16%	425
July	1st to 10th	Night	8% 2 20% 40% 26% 3	555
	11th to 20th	Night	9% 3 21% 41% 23% 4	552
	21st to end	Night	6% 4 20% 45% 23% 2	624
August	1st to 10th	Night	8% 4 16% 40% 30% 2	567
	11th to 20th	Night	8% 2 19% 39% 27% 4	564
	21st to end	Night	11% 3 19% 36% 29% 3	627
September	1st to 10th	Night	12% 5% 21% 35% 23% 5%	689
	11th to 20th	Night	10% 4 19% 34% 29% 4	760
	21st to end	Night	17% 7% 22% 33% 19% 3	760
October	1st to 10th	Night	15% 8% 28% 29% 17% 2	760
	11th to 20th	Night	21% 15% 29% 26% 8% 1	760
	21st to end	Night	24% 14% 33% 25% 5%	836
November	1st to 10th	Night	19% 12% 30% 26% 12% 1	755
	11th to 20th	Night	19% 16% 35% 22% 6% 1	760
	21st to end	Night	23% 15% 36% 20% 5%	760
December	1st to 10th	Night	23% 16% 37% 20% 5%	760
	11th to 20th	Night	21% 14% 41% 21% 3	878
	21st to end	Night	28% 14% 35% 21% 2	1045

Page generated at 2024-11-01 22:47:51. Version ac07

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