South Haven Pier
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the South Haven Pier clear sky chart from 2005-11-06 to 2024-11-08.

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% 11% 4 8% 5% 4 4 3 5% 7% 36%	101262
	Night	16% 13% 5% 9% 5% 4 4 3 4 6% 31%	97891
Transparency	Day	49% 3 11% 23% 13% 1	104846
	Night	55% 3 10% 19% 12% 1	102448
Seeing	Day	20% 16% 30% 21% 10% 3	15814
	Night	22% 14% 27% 25% 11% 1	25657

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	15% 26% 10% 13% 8% 4 3 3 4 4 10%	2527
	11th to 20th	Day	13% 21% 7% 18% 13% 9% 4 2 2 2 7%	2530
	21st to end	Day	24% 24% 9% 14% 6% 3 3 2 3 3 10%	2783
February	1st to 10th	Day	14% 18% 6% 17% 11% 5% 4 3 3 3 17%	1772
	11th to 20th	Day	14% 15% 6% 18% 8% 4 3 3 4 4 21%	1848
	21st to end	Day	16% 14% 6% 13% 6% 5% 4 3 5% 6% 22%	1570
March	1st to 10th	Day	16% 13% 5% 7% 5% 4 5% 2 5% 7% 30%	3120
	11th to 20th	Day	11% 9% 9% 10% 4 4 4 3 6% 7% 32%	3342
	21st to end	Day	19% 12% 7% 10% 5% 4 4 3 4 5% 26%	4026
April	1st to 10th	Day	18% 13% 3 6% 4 4 4 4 5% 7% 31%	2280
	11th to 20th	Day	16% 11% 3 6% 3 3 4 3 5% 6% 40%	2270
	21st to end	Day	18% 9% 3 7% 4 4 4 3 6% 7% 36%	2470
May	1st to 10th	Day	17% 7% 2 6% 4 4 5% 4 5% 7% 39%	4082
	11th to 20th	Day	15% 6% 3 6% 4 3 4 4 5% 8% 43%	4111
	21st to end	Day	11% 5% 2 6% 4 3 4 3 6% 8% 48%	4824
June	1st to 10th	Day	11% 5% 2 6% 4 4 4 4 6% 7% 48%	2660
	11th to 20th	Day	9% 5% 2 5% 4 4 4 4 7% 8% 48%	2660
	21st to end	Day	12% 6% 2 6% 4 4 3 4 6% 8% 46%	2660
July	1st to 10th	Day	13% 7% 2 6% 4 4 4 3 6% 10% 40%	4440
	11th to 20th	Day	7% 4 1 4 3 4 4 4 6% 9% 53%	4440
	21st to end	Day	7% 5% 2 6% 4 4 4 4 7% 9% 49%	4813
August	1st to 10th	Day	12% 5% 2 5% 4 3 4 3 6% 8% 48%	4175
	11th to 20th	Day	11% 5% 2 5% 3 4 4 4 5% 7% 51%	3991
	21st to end	Day	8% 4 2 6% 4 4 3 3 5% 9% 50%	4180
September	1st to 10th	Day	11% 6% 2 5% 4 4 5% 3 6% 8% 47%	2273
	11th to 20th	Day	12% 5% 2 4 3 4 4 3 6% 8% 48%	2090
	21st to end	Day	12% 7% 2 7% 5% 3 5% 3 6% 8% 40%	2090
October	1st to 10th	Day	17% 7% 3 6% 4 4 4 3 3 5% 44%	2090
	11th to 20th	Day	24% 10% 2 8% 5% 4 4 3 5% 7% 27%	1854
	21st to end	Day	26% 12% 3 7% 5% 5% 5% 4 5% 5% 23%	1881
November	1st to 10th	Day	16% 15% 3 6% 4 4 4 3 4 6% 36%	1735
	11th to 20th	Day	16% 25% 5% 9% 4 4 4 3 3 5% 21%	1710
	21st to end	Day	23% 21% 6% 9% 5% 3 3 2 4 4 20%	1710
December	1st to 10th	Day	16% 29% 9% 11% 6% 3 2 3 3 4 15%	1554
	11th to 20th	Day	14% 25% 13% 12% 4 3 4 3 4 5% 13%	1918
	21st to end	Day	23% 25% 9% 12% 5% 3 3 2 3 4 10%	2783
January	1st to 10th	Night	17% 27% 11% 13% 6% 4 3 3 3 3 10%	4428
	11th to 20th	Night	16% 22% 11% 17% 9% 9% 3 2 2 2 8%	4440
	21st to end	Night	25% 21% 12% 15% 5% 4 3 2 2 3 8%	4884
February	1st to 10th	Night	14% 18% 6% 17% 9% 4 3 2 4 4 18%	2401
	11th to 20th	Night	14% 18% 8% 14% 7% 4 3 3 4 4 20%	2218
	21st to end	Night	18% 17% 5% 12% 6% 4 2 3 4 4 24%	1884
March	1st to 10th	Night	17% 11% 5% 9% 4 4 3 3 4 5% 34%	3733
	11th to 20th	Night	10% 9% 4 8% 5% 5% 4 4 4 6% 42%	3618
	21st to end	Night	19% 13% 7% 10% 5% 4 4 3 4 5% 27%	3635
April	1st to 10th	Night	14% 12% 3 7% 5% 5% 5% 4 5% 6% 35%	1900
	11th to 20th	Night	20% 10% 3 6% 4 3 4 4 4 5% 37%	1857
	21st to end	Night	18% 8% 3 6% 4 4 4 3 6% 7% 37%	1710
May	1st to 10th	Night	16% 8% 3 7% 5% 4 4 4 5% 8% 35%	2813
	11th to 20th	Night	18% 7% 3 6% 4 4 3 3 4 7% 41%	2768
	21st to end	Night	16% 6% 2 6% 4 4 4 3 5% 7% 42%	2743
June	1st to 10th	Night	10% 4 2 6% 4 4 4 4 7% 9% 47%	1520
	11th to 20th	Night	9% 6% 2 7% 5% 4 4 4 6% 8% 45%	1520
	21st to end	Night	10% 5% 3 5% 5% 4 6% 4 6% 9% 43%	1520
July	1st to 10th	Night	10% 6% 2 7% 5% 5% 5% 4 6% 9% 41%	2530
	11th to 20th	Night	8% 4 1 5% 4 3 4 4 6% 8% 55%	2530
	21st to end	Night	7% 5% 3 6% 5% 5% 5% 4 6% 10% 46%	2750
August	1st to 10th	Night	10% 4 2 6% 4 5% 4 4 6% 8% 47%	2754
	11th to 20th	Night	12% 4 2 4 4 4 4 3 5% 7% 51%	2835
	21st to end	Night	9% 6% 2 7% 4 4 5% 4 5% 7% 47%	3476
September	1st to 10th	Night	11% 6% 2 6% 4 3 4 3 5% 7% 50%	1900
	11th to 20th	Night	12% 4 2 4 3 4 4 3 5% 7% 52%	2077
	21st to end	Night	13% 8% 3 8% 4 4 4 4 5% 7% 41%	2090
October	1st to 10th	Night	17% 7% 2 6% 3 4 3 3 5% 5% 45%	2090
	11th to 20th	Night	22% 11% 4 6% 4 3 3 3 4 5% 35%	2321
	21st to end	Night	27% 12% 3 6% 4 3 4 2 4 6% 29%	2717
November	1st to 10th	Night	17% 15% 4 7% 4 4 3 4 4 5% 35%	2504
	11th to 20th	Night	18% 23% 6% 9% 4 3 3 3 4 5% 23%	2470
	21st to end	Night	19% 22% 5% 8% 4 3 3 2 4 5% 24%	2470
December	1st to 10th	Night	19% 29% 7% 10% 4 3 3 2 4 4 14%	2622
	11th to 20th	Night	17% 24% 12% 12% 5% 3 3 3 4 4 13%	3279
	21st to end	Night	27% 23% 7% 9% 5% 4 4 2 3 4 11%	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	80% 2 8% 8% 1	2528
	11th to 20th	Day	87% 2 6% 4 1	2530
	21st to end	Day	84% 1 7% 7% 2	2783
February	1st to 10th	Day	75% 2 8% 11% 4 1	1772
	11th to 20th	Day	68% 3 8% 14% 6% 1	1858
	21st to end	Day	64% 3 11% 15% 5% 1	1570
March	1st to 10th	Day	57% 2 12% 21% 8%	3120
	11th to 20th	Day	53% 2 11% 26% 7% 1	3342
	21st to end	Day	62% 2 9% 21% 5% 1	4026
April	1st to 10th	Day	54% 3 9% 21% 12%	2280
	11th to 20th	Day	46% 3 9% 25% 14% 3	2270
	21st to end	Day	49% 4 11% 20% 14% 2	2470
May	1st to 10th	Day	46% 3 10% 27% 13% 1	4120
	11th to 20th	Day	42% 3 13% 27% 15% 1	4115
	21st to end	Day	35% 3 11% 27% 23% 1	4837
June	1st to 10th	Day	35% 4 11% 28% 20% 2	2660
	11th to 20th	Day	33% 5% 13% 27% 21% 2	2660
	21st to end	Day	37% 4 15% 24% 17% 2	2660
July	1st to 10th	Day	41% 4 14% 23% 15% 3	4371
	11th to 20th	Day	27% 4 15% 34% 18% 2	4365
	21st to end	Day	32% 6% 17% 22% 21% 2	4662
August	1st to 10th	Day	35% 4 13% 31% 15% 1	4160
	11th to 20th	Day	33% 5% 13% 34% 14% 1	4030
	21st to end	Day	32% 4 14% 29% 18% 2	4179
September	1st to 10th	Day	36% 4 13% 27% 15% 4	2273
	11th to 20th	Day	34% 3 12% 33% 17% 2	2090
	21st to end	Day	42% 3 9% 28% 16% 1	2090
October	1st to 10th	Day	31% 3 8% 40% 17% 1	3480
	11th to 20th	Day	43% 4 10% 24% 18%	3057
	21st to end	Day	54% 3 11% 23% 9% 1	3081
November	1st to 10th	Day	52% 4 12% 20% 12% 1	1735
	11th to 20th	Day	67% 2 9% 16% 5% 1	1710
	21st to end	Day	69% 3 11% 13% 4	1710
December	1st to 10th	Day	76% 3 8% 10% 3	1554
	11th to 20th	Day	76% 2 11% 9% 1	1915
	21st to end	Day	81% 2 7% 9% 1	2783
January	1st to 10th	Night	81% 2 7% 7% 3	4428
	11th to 20th	Night	85% 2 6% 5% 2	4440
	21st to end	Night	85% 1 7% 5% 1	4884
February	1st to 10th	Night	72% 3 8% 11% 6%	2401
	11th to 20th	Night	69% 3 6% 16% 6%	2219
	21st to end	Night	65% 2 10% 15% 7% 1	1884
March	1st to 10th	Night	54% 3 12% 24% 7%	3733
	11th to 20th	Night	45% 4 11% 25% 13% 2	3618
	21st to end	Night	62% 2 10% 18% 7% 1	3635
April	1st to 10th	Night	50% 4 11% 21% 13% 1	1900
	11th to 20th	Night	50% 3 7% 19% 18% 3	1857
	21st to end	Night	47% 4 11% 20% 15% 3	1710
May	1st to 10th	Night	49% 2 10% 25% 13% 1	2840
	11th to 20th	Night	45% 2 9% 24% 17% 3	2769
	21st to end	Night	43% 3 9% 20% 23% 2	2751
June	1st to 10th	Night	34% 4 11% 31% 17% 3	1520
	11th to 20th	Night	37% 4 11% 26% 19% 3	1520
	21st to end	Night	38% 5% 15% 24% 16% 3	1520
July	1st to 10th	Night	39% 4 14% 24% 12% 7%	2490
	11th to 20th	Night	27% 6% 12% 25% 26% 3	2482
	21st to end	Night	34% 6% 14% 18% 26% 2	2662
August	1st to 10th	Night	34% 5% 13% 29% 17% 1	2745
	11th to 20th	Night	34% 5% 9% 32% 19% 1	2862
	21st to end	Night	36% 4 9% 28% 20% 2	3476
September	1st to 10th	Night	35% 4 11% 28% 18% 4	1900
	11th to 20th	Night	33% 3 8% 32% 22% 2	2077
	21st to end	Night	43% 4 10% 26% 16% 1	2090
October	1st to 10th	Night	31% 3 8% 34% 23% 1	3480
	11th to 20th	Night	43% 3 10% 23% 20% 1	3857
	21st to end	Night	47% 3 8% 26% 15% 1	4467
November	1st to 10th	Night	53% 3 8% 21% 13% 1	2504
	11th to 20th	Night	65% 2 10% 16% 6% 1	2470
	21st to end	Night	66% 2 13% 16% 3	2470
December	1st to 10th	Night	77% 2 7% 9% 4	2622
	11th to 20th	Night	76% 4 10% 8% 2	3281
	21st to end	Night	80% 2 10% 7% 1	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	23% 25% 31% 16% 3 1	270
	11th to 20th	Day	24% 20% 39% 14% 3	270
	21st to end	Day	32% 21% 32% 14% 1	297
February	1st to 10th	Day	28% 27% 27% 14% 4 1	270
	11th to 20th	Day	27% 31% 30% 10% 1	270
	21st to end	Day	31% 33% 27% 9%	225
March	1st to 10th	Day	23% 35% 30% 11% 2	270
	11th to 20th	Day	25% 23% 31% 17% 4 1	374
	21st to end	Day	32% 20% 28% 15% 5% 1	506
April	1st to 10th	Day	27% 23% 31% 14% 5%	460
	11th to 20th	Day	27% 25% 28% 13% 6% 2	452
	21st to end	Day	26% 21% 30% 15% 7% 1	460
May	1st to 10th	Day	24% 19% 32% 18% 5% 2	463
	11th to 20th	Day	20% 15% 33% 21% 7% 5%	504
	21st to end	Day	13% 13% 35% 22% 12% 4	734
June	1st to 10th	Day	12% 13% 37% 24% 11% 4	680
	11th to 20th	Day	13% 12% 33% 29% 10% 3	680
	21st to end	Day	15% 11% 37% 24% 11% 3	680
July	1st to 10th	Day	10% 8% 29% 31% 16% 7%	671
	11th to 20th	Day	9% 9% 31% 32% 11% 7%	668
	21st to end	Day	7% 7% 33% 33% 15% 5%	739
August	1st to 10th	Day	10% 6% 24% 30% 20% 10%	532
	11th to 20th	Day	11% 7% 26% 27% 21% 7%	479
	21st to end	Day	12% 7% 24% 32% 19% 6%	539
September	1st to 10th	Day	14% 9% 25% 30% 17% 6%	490
	11th to 20th	Day	10% 6% 23% 27% 26% 8%	490
	21st to end	Day	18% 15% 23% 22% 16% 6%	490
October	1st to 10th	Day	21% 12% 28% 23% 13% 3	490
	11th to 20th	Day	29% 20% 29% 18% 4	363
	21st to end	Day	38% 19% 29% 11% 3	330
November	1st to 10th	Day	29% 20% 30% 15% 5% 1	291
	11th to 20th	Day	30% 26% 28% 13% 3	270
	21st to end	Day	33% 25% 31% 10%	270
December	1st to 10th	Day	31% 30% 24% 11% 4	270
	11th to 20th	Day	26% 29% 30% 13% 2 1	270
	21st to end	Day	29% 29% 33% 8% 1	297
January	1st to 10th	Night	27% 23% 28% 17% 4	950
	11th to 20th	Night	30% 18% 31% 17% 4 1	950
	21st to end	Night	26% 18% 32% 21% 3	1045
February	1st to 10th	Night	24% 20% 33% 19% 4	809
	11th to 20th	Night	24% 21% 32% 19% 4	743
	21st to end	Night	29% 21% 32% 16% 2	628
March	1st to 10th	Night	23% 19% 28% 23% 6% 1	760
	11th to 20th	Night	21% 16% 34% 22% 6% 1	760
	21st to end	Night	25% 14% 29% 25% 6% 1	731
April	1st to 10th	Night	21% 18% 31% 23% 7% 1	570
	11th to 20th	Night	27% 14% 28% 23% 6% 1	563
	21st to end	Night	22% 13% 29% 27% 7% 2	570
May	1st to 10th	Night	19% 12% 32% 28% 8% 1	570
	11th to 20th	Night	19% 10% 26% 32% 13%	561
	21st to end	Night	15% 6% 27% 33% 18% 2	617
June	1st to 10th	Night	12% 6% 26% 38% 18% 1	570
	11th to 20th	Night	12% 5% 31% 35% 17% 1	570
	21st to end	Night	11% 7% 24% 35% 21% 2	570
July	1st to 10th	Night	9% 3 20% 36% 28% 4	555
	11th to 20th	Night	9% 5% 21% 33% 28% 4	552
	21st to end	Night	8% 4 18% 42% 26% 2	624
August	1st to 10th	Night	8% 4 16% 43% 26% 4	567
	11th to 20th	Night	11% 4 15% 39% 27% 5%	564
	21st to end	Night	10% 6% 18% 36% 28% 3	627
September	1st to 10th	Night	13% 7% 18% 36% 23% 4	570
	11th to 20th	Night	13% 6% 17% 33% 27% 3	747
	21st to end	Night	19% 10% 22% 26% 18% 4	760
October	1st to 10th	Night	19% 9% 24% 29% 17% 2	760
	11th to 20th	Night	29% 15% 25% 23% 7% 1	760
	21st to end	Night	34% 15% 26% 19% 5%	836
November	1st to 10th	Night	26% 16% 29% 20% 9% 1	771
	11th to 20th	Night	32% 21% 27% 16% 3 1	760
	21st to end	Night	33% 16% 31% 17% 3	760
December	1st to 10th	Night	33% 21% 29% 14% 3	912
	11th to 20th	Night	30% 20% 31% 15% 3 1	950
	21st to end	Night	36% 20% 29% 13% 1	1045

Page generated at 2024-11-05 08:15:51. Version ac07

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