Beaver Dam
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Beaver Dam clear sky chart from 2005-11-06 to 2024-11-10.

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% 9% 3 8% 5% 4 4 4 6% 7% 38%	101501
	Night	13% 10% 3 8% 4 4 4 3 5% 6% 38%	97723
Transparency	Day	43% 6% 12% 24% 13% 1	105018
	Night	44% 6% 11% 23% 14% 2	102334
Seeing	Day	16% 10% 28% 27% 15% 5%	15938
	Night	17% 9% 31% 31% 12% 1	25792

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	11% 14% 7% 14% 6% 5% 4 4 5% 5% 26%	2527
	11th to 20th	Day	10% 13% 5% 14% 7% 4 7% 7% 7% 7% 19%	2530
	21st to end	Day	17% 16% 9% 13% 6% 5% 3 4 4 5% 19%	2829
February	1st to 10th	Day	11% 12% 6% 10% 6% 5% 6% 4 5% 6% 30%	1710
	11th to 20th	Day	12% 11% 3 7% 5% 5% 5% 4 5% 7% 36%	1801
	21st to end	Day	11% 13% 4 9% 6% 5% 5% 5% 5% 7% 31%	1570
March	1st to 10th	Day	12% 8% 2 6% 4 4 4 3 5% 6% 44%	3120
	11th to 20th	Day	11% 6% 3 8% 5% 4 4 3 6% 7% 44%	3305
	21st to end	Day	22% 11% 4 11% 4 3 4 3 4 6% 28%	4157
April	1st to 10th	Day	17% 13% 4 7% 5% 4 4 3 5% 7% 30%	2280
	11th to 20th	Day	17% 10% 3 7% 5% 5% 4 4 5% 6% 34%	2254
	21st to end	Day	19% 10% 2 6% 5% 4 5% 3 6% 7% 33%	2382
May	1st to 10th	Day	14% 8% 3 7% 4 4 4 4 6% 7% 40%	4194
	11th to 20th	Day	13% 6% 2 7% 4 4 4 3 5% 7% 45%	4399
	21st to end	Day	13% 8% 3 7% 4 4 5% 4 6% 8% 39%	4824
June	1st to 10th	Day	10% 6% 2 6% 4 4 5% 4 6% 8% 44%	2660
	11th to 20th	Day	12% 6% 2 6% 5% 4 6% 3 6% 8% 42%	2660
	21st to end	Day	11% 6% 2 6% 3 4 5% 5% 7% 10% 42%	2660
July	1st to 10th	Day	11% 7% 3 7% 5% 4 5% 5% 8% 10% 35%	4440
	11th to 20th	Day	4 4 1 4 3 5% 5% 5% 7% 10% 51%	4440
	21st to end	Day	8% 6% 2 6% 4 4 5% 4 7% 9% 44%	4813
August	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 4 7% 9% 41%	4423
	11th to 20th	Day	12% 5% 2 6% 3 4 3 3 5% 8% 48%	3819
	21st to end	Day	10% 6% 2 6% 5% 4 4 4 6% 9% 44%	4180
September	1st to 10th	Day	12% 6% 2 5% 4 5% 5% 3 6% 8% 45%	2280
	11th to 20th	Day	12% 5% 2 5% 4 4 4 3 5% 8% 50%	2196
	21st to end	Day	12% 8% 2 7% 4 4 4 4 6% 7% 43%	2090
October	1st to 10th	Day	13% 7% 3 6% 4 4 4 3 4 7% 46%	1972
	11th to 20th	Day	20% 10% 2 7% 5% 4 4 3 6% 7% 32%	1896
	21st to end	Day	17% 10% 3 8% 5% 4 4 4 4 5% 37%	1881
November	1st to 10th	Day	13% 8% 2 7% 4 4 4 3 6% 7% 42%	1753
	11th to 20th	Day	12% 13% 4 10% 7% 5% 4 3 5% 7% 30%	1710
	21st to end	Day	17% 11% 3 9% 5% 3 4 2 5% 6% 34%	1525
December	1st to 10th	Day	12% 15% 4 11% 7% 6% 5% 3 4 6% 27%	1520
	11th to 20th	Day	13% 15% 5% 9% 6% 5% 5% 3 5% 7% 26%	1918
	21st to end	Day	18% 21% 8% 15% 6% 5% 4 2 4 4 13%	2783
January	1st to 10th	Night	12% 15% 7% 10% 5% 4 4 2 4 4 31%	4428
	11th to 20th	Night	11% 14% 6% 16% 6% 5% 5% 6% 6% 5% 20%	4440
	21st to end	Night	15% 19% 8% 12% 5% 5% 3 2 4 4 23%	4820
February	1st to 10th	Night	9% 15% 5% 9% 5% 5% 4 3 5% 6% 33%	2470
	11th to 20th	Night	11% 10% 3 9% 5% 5% 4 4 5% 5% 40%	2264
	21st to end	Night	16% 13% 4 7% 4 4 5% 3 4 5% 35%	1884
March	1st to 10th	Night	15% 9% 2 6% 4 4 4 3 4 5% 43%	3733
	11th to 20th	Night	10% 7% 3 5% 4 4 4 4 6% 9% 45%	3685
	21st to end	Night	21% 11% 4 10% 4 4 4 3 4 5% 31%	3473
April	1st to 10th	Night	18% 11% 3 6% 4 4 4 3 5% 5% 36%	1900
	11th to 20th	Night	20% 9% 3 6% 4 5% 3 3 5% 6% 37%	1875
	21st to end	Night	18% 8% 3 6% 4 4 3 4 5% 7% 38%	1796
May	1st to 10th	Night	16% 8% 3 7% 5% 4 5% 4 6% 8% 35%	2703
	11th to 20th	Night	13% 6% 2 6% 4 5% 5% 4 6% 7% 42%	2506
	21st to end	Night	14% 7% 2 6% 4 5% 4 4 5% 6% 40%	2743
June	1st to 10th	Night	9% 5% 2 4 4 5% 4 4 7% 8% 47%	1520
	11th to 20th	Night	11% 5% 2 6% 4 4 4 4 5% 10% 47%	1520
	21st to end	Night	9% 5% 2 5% 4 3 4 4 6% 8% 48%	1520
July	1st to 10th	Night	13% 8% 2 6% 3 4 4 4 6% 8% 43%	2530
	11th to 20th	Night	4 3 2 4 3 4 5% 4 6% 9% 57%	2530
	21st to end	Night	7% 5% 2 6% 4 5% 5% 5% 7% 9% 47%	2750
August	1st to 10th	Night	11% 5% 2 6% 3 4 3 4 6% 8% 48%	2517
	11th to 20th	Night	10% 6% 3 7% 3 4 4 4 5% 8% 46%	3007
	21st to end	Night	8% 5% 2 5% 4 4 5% 4 6% 9% 48%	3476
September	1st to 10th	Night	9% 5% 2 5% 3 3 4 3 5% 6% 55%	1900
	11th to 20th	Night	12% 4 2 6% 3 4 5% 3 5% 6% 50%	1964
	21st to end	Night	11% 6% 2 6% 3 3 4 3 6% 7% 49%	2090
October	1st to 10th	Night	12% 6% 2 6% 4 3 3 3 5% 6% 49%	2204
	11th to 20th	Night	17% 8% 2 6% 4 3 4 3 5% 6% 41%	2283
	21st to end	Night	19% 11% 2 7% 4 4 4 3 5% 6% 35%	2717
November	1st to 10th	Night	14% 7% 2 7% 4 4 4 3 5% 6% 44%	2530
	11th to 20th	Night	14% 12% 5% 8% 6% 4 4 3 6% 6% 32%	2470
	21st to end	Night	16% 11% 2 7% 5% 4 4 3 5% 6% 37%	2652
December	1st to 10th	Night	13% 13% 4 10% 6% 5% 4 4 4 7% 30%	2660
	11th to 20th	Night	14% 15% 5% 10% 6% 5% 5% 3 5% 4 28%	3279
	21st to end	Night	21% 18% 6% 11% 5% 4 4 3 5% 5% 20%	4884

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	59% 7% 14% 14% 5%	2528
	11th to 20th	Day	60% 6% 12% 16% 5%	2530
	21st to end	Day	67% 4 10% 14% 5%	2829
February	1st to 10th	Day	54% 5% 13% 18% 8% 1	1710
	11th to 20th	Day	47% 7% 12% 23% 10% 2	1811
	21st to end	Day	53% 6% 10% 18% 10% 2	1570
March	1st to 10th	Day	39% 6% 11% 28% 14% 2	3120
	11th to 20th	Day	39% 6% 11% 28% 14% 1	3305
	21st to end	Day	58% 6% 10% 18% 8% 1	4157
April	1st to 10th	Day	52% 7% 11% 19% 10%	2280
	11th to 20th	Day	49% 7% 10% 20% 13% 2	2254
	21st to end	Day	49% 8% 11% 20% 11% 1	2382
May	1st to 10th	Day	42% 7% 12% 23% 16% 1	4232
	11th to 20th	Day	38% 7% 11% 30% 14% 1	4403
	21st to end	Day	41% 8% 11% 22% 16% 2	4837
June	1st to 10th	Day	36% 8% 13% 27% 15% 1	2660
	11th to 20th	Day	39% 6% 13% 24% 16% 1	2660
	21st to end	Day	36% 10% 15% 24% 14% 2	2660
July	1st to 10th	Day	42% 7% 13% 27% 9% 2	4371
	11th to 20th	Day	26% 7% 16% 32% 17% 1	4365
	21st to end	Day	34% 8% 15% 21% 19% 2	4662
August	1st to 10th	Day	37% 8% 14% 28% 12% 1	4408
	11th to 20th	Day	34% 5% 12% 36% 12% 1	3857
	21st to end	Day	37% 6% 14% 27% 16% 1	4179
September	1st to 10th	Day	37% 8% 12% 25% 18% 1	2280
	11th to 20th	Day	33% 6% 13% 31% 15% 1	2196
	21st to end	Day	39% 5% 11% 30% 13% 1	2090
October	1st to 10th	Day	24% 4 6% 39% 25% 2	3271
	11th to 20th	Day	38% 5% 9% 27% 20% 1	3124
	21st to end	Day	42% 4 12% 28% 13% 1	3081
November	1st to 10th	Day	41% 5% 16% 22% 14% 2	1753
	11th to 20th	Day	53% 6% 13% 20% 8% 1	1710
	21st to end	Day	52% 5% 14% 22% 7%	1525
December	1st to 10th	Day	58% 5% 14% 15% 7% 1	1520
	11th to 20th	Day	55% 6% 15% 16% 6% 2	1915
	21st to end	Day	74% 5% 8% 8% 5%	2783
January	1st to 10th	Night	56% 5% 10% 20% 8% 1	4428
	11th to 20th	Night	63% 6% 10% 13% 8%	4440
	21st to end	Night	65% 5% 10% 14% 5%	4820
February	1st to 10th	Night	52% 5% 10% 20% 12% 2	2470
	11th to 20th	Night	46% 5% 11% 22% 14% 1	2265
	21st to end	Night	50% 6% 11% 19% 12% 2	1884
March	1st to 10th	Night	43% 5% 12% 25% 10% 4	3733
	11th to 20th	Night	34% 6% 11% 27% 18% 3	3685
	21st to end	Night	56% 6% 8% 18% 10% 2	3473
April	1st to 10th	Night	48% 7% 9% 20% 15% 1	1900
	11th to 20th	Night	48% 4 9% 19% 17% 3	1875
	21st to end	Night	44% 7% 13% 21% 14% 2	1796
May	1st to 10th	Night	43% 7% 14% 17% 17% 1	2730
	11th to 20th	Night	38% 9% 11% 27% 14% 1	2507
	21st to end	Night	41% 9% 10% 18% 17% 5%	2751
June	1st to 10th	Night	32% 9% 14% 27% 19% 1	1520
	11th to 20th	Night	33% 7% 11% 28% 19% 3	1520
	21st to end	Night	32% 8% 16% 24% 18% 2	1520
July	1st to 10th	Night	39% 7% 15% 22% 13% 4	2490
	11th to 20th	Night	24% 7% 15% 34% 19% 2	2482
	21st to end	Night	31% 9% 15% 21% 21% 3	2662
August	1st to 10th	Night	33% 6% 15% 24% 20% 2	2508
	11th to 20th	Night	34% 7% 12% 32% 15%	3035
	21st to end	Night	31% 7% 14% 26% 19% 3	3476
September	1st to 10th	Night	29% 8% 11% 27% 24% 2	1900
	11th to 20th	Night	34% 6% 10% 32% 18% 1	1964
	21st to end	Night	35% 6% 11% 30% 17% 2	2090
October	1st to 10th	Night	26% 4 6% 38% 25% 2	3672
	11th to 20th	Night	33% 4 11% 30% 19% 2	3794
	21st to end	Night	44% 4 9% 26% 15% 1	4467
November	1st to 10th	Night	41% 6% 11% 26% 15% 2	2530
	11th to 20th	Night	51% 6% 13% 18% 11% 1	2470
	21st to end	Night	49% 6% 14% 22% 9% 1	2652
December	1st to 10th	Night	54% 6% 12% 19% 8% 1	2660
	11th to 20th	Night	59% 6% 10% 17% 7% 1	3281
	21st to end	Night	67% 6% 9% 13% 5%	4884

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	14% 12% 33% 30% 9% 1	270
	11th to 20th	Day	16% 13% 34% 28% 9% 1	270
	21st to end	Day	21% 10% 34% 28% 6% 1	297
February	1st to 10th	Day	13% 14% 41% 23% 7% 1	270
	11th to 20th	Day	17% 19% 33% 23% 7%	270
	21st to end	Day	16% 16% 43% 23% 2	225
March	1st to 10th	Day	15% 16% 42% 22% 3 1	270
	11th to 20th	Day	20% 14% 31% 23% 8% 3	270
	21st to end	Day	25% 11% 31% 23% 7% 2	498
April	1st to 10th	Day	26% 11% 33% 25% 5%	460
	11th to 20th	Day	25% 15% 28% 19% 10% 2	452
	21st to end	Day	22% 12% 29% 23% 12% 2	460
May	1st to 10th	Day	19% 11% 34% 24% 10% 2	523
	11th to 20th	Day	20% 8% 29% 26% 14% 3	675
	21st to end	Day	17% 10% 27% 25% 15% 6%	734
June	1st to 10th	Day	11% 7% 28% 32% 18% 4	680
	11th to 20th	Day	14% 7% 30% 29% 15% 5%	680
	21st to end	Day	15% 7% 26% 31% 17% 4	680
July	1st to 10th	Day	8% 4 18% 32% 25% 12%	671
	11th to 20th	Day	9% 4 24% 33% 21% 8%	668
	21st to end	Day	7% 3 25% 34% 24% 8%	739
August	1st to 10th	Day	8% 4 20% 33% 25% 11%	676
	11th to 20th	Day	14% 5% 15% 27% 25% 14%	515
	21st to end	Day	12% 7% 18% 29% 23% 11%	539
September	1st to 10th	Day	15% 6% 22% 26% 23% 8%	490
	11th to 20th	Day	11% 4 20% 30% 24% 11%	490
	21st to end	Day	16% 10% 25% 25% 18% 6%	490
October	1st to 10th	Day	18% 11% 23% 27% 17% 4	372
	11th to 20th	Day	24% 15% 31% 20% 10% 1	300
	21st to end	Day	23% 15% 35% 21% 5% 2	330
November	1st to 10th	Day	15% 16% 37% 22% 9% 1	297
	11th to 20th	Day	15% 18% 37% 19% 10%	270
	21st to end	Day	23% 13% 38% 19% 7%	270
December	1st to 10th	Day	19% 16% 42% 16% 7%	270
	11th to 20th	Day	21% 13% 34% 20% 11% 1	270
	21st to end	Day	26% 15% 38% 17% 4	297
January	1st to 10th	Night	17% 15% 35% 25% 7% 1	950
	11th to 20th	Night	19% 12% 35% 26% 6% 1	950
	21st to end	Night	19% 10% 36% 29% 5% 1	1045
February	1st to 10th	Night	17% 12% 37% 27% 7% 1	950
	11th to 20th	Night	17% 13% 35% 28% 6%	789
	21st to end	Night	22% 14% 37% 23% 4 1	628
March	1st to 10th	Night	19% 10% 34% 29% 7% 1	760
	11th to 20th	Night	17% 10% 35% 30% 8% 1	697
	21st to end	Night	22% 8% 29% 31% 9% 1	627
April	1st to 10th	Night	22% 12% 36% 25% 5%	570
	11th to 20th	Night	22% 11% 32% 28% 7%	563
	21st to end	Night	22% 9% 31% 29% 9% 1	570
May	1st to 10th	Night	18% 9% 34% 31% 7%	570
	11th to 20th	Night	17% 7% 33% 31% 11%	561
	21st to end	Night	13% 5% 28% 37% 17% 1	617
June	1st to 10th	Night	9% 5% 26% 43% 15% 1	570
	11th to 20th	Night	13% 4 30% 39% 14% 1	570
	21st to end	Night	11% 5% 26% 42% 16%	570
July	1st to 10th	Night	8% 2 17% 39% 31% 3	555
	11th to 20th	Night	6% 4 19% 46% 23% 3	552
	21st to end	Night	6% 2 17% 50% 24% 2	624
August	1st to 10th	Night	9% 2 14% 47% 25% 2	567
	11th to 20th	Night	10% 3 15% 40% 28% 4	564
	21st to end	Night	11% 2 18% 43% 24% 3	627
September	1st to 10th	Night	10% 4 23% 38% 21% 5%	570
	11th to 20th	Night	12% 4 22% 35% 24% 4	634
	21st to end	Night	12% 8% 29% 30% 20% 2	760
October	1st to 10th	Night	15% 6% 29% 33% 16% 1	760
	11th to 20th	Night	21% 11% 32% 27% 9%	760
	21st to end	Night	24% 10% 31% 28% 7% 1	836
November	1st to 10th	Night	18% 10% 36% 25% 9% 1	779
	11th to 20th	Night	21% 14% 37% 22% 6% 1	760
	21st to end	Night	21% 13% 34% 24% 7%	942
December	1st to 10th	Night	21% 13% 40% 21% 6%	950
	11th to 20th	Night	23% 13% 35% 23% 6% 1	950
	21st to end	Night	28% 12% 34% 22% 4	1045

Page generated at 2024-11-07 05:55:43. Version ac07

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