Saginaw
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saginaw 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% 35%	100984
	Night	14% 11% 4 8% 5% 4 4 3 5% 6% 35%	98036
Transparency	Day	47% 6% 12% 22% 12% 1	104582
	Night	48% 5% 12% 22% 12% 1	102578
Seeing	Day	17% 10% 28% 25% 15% 6%	15532
	Night	19% 8% 29% 31% 12% 1	25255

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% 18% 7% 12% 7% 4 5% 3 4 4 21%	2527
	11th to 20th	Day	14% 19% 7% 16% 12% 8% 5% 3 3 4 8%	2530
	21st to end	Day	23% 22% 7% 11% 6% 5% 4 3 3 4 12%	2907
February	1st to 10th	Day	11% 16% 4 13% 7% 6% 6% 4 5% 6% 22%	1710
	11th to 20th	Day	13% 15% 5% 11% 8% 6% 5% 3 4 5% 25%	1800
	21st to end	Day	14% 14% 5% 11% 7% 5% 5% 3 5% 6% 26%	1570
March	1st to 10th	Day	16% 13% 3 8% 5% 5% 4 3 5% 6% 31%	3144
	11th to 20th	Day	12% 13% 5% 9% 6% 5% 5% 4 5% 6% 31%	3480
	21st to end	Day	18% 12% 4 9% 5% 4 5% 4 5% 6% 29%	3815
April	1st to 10th	Day	18% 12% 4 7% 5% 4 5% 3 5% 6% 30%	2256
	11th to 20th	Day	17% 9% 3 7% 4 4 3 4 6% 6% 36%	2394
	21st to end	Day	17% 8% 3 8% 6% 5% 3 4 4 6% 35%	2470
May	1st to 10th	Day	16% 9% 3 6% 4 4 5% 4 5% 8% 36%	4082
	11th to 20th	Day	15% 6% 3 6% 4 4 5% 4 6% 8% 38%	4081
	21st to end	Day	11% 6% 2 6% 4 4 4 3 5% 8% 46%	4654
June	1st to 10th	Day	11% 7% 2 6% 4 4 5% 4 7% 8% 42%	2760
	11th to 20th	Day	11% 6% 2 6% 5% 4 4 3 6% 9% 44%	2850
	21st to end	Day	10% 5% 2 6% 5% 6% 5% 4 8% 9% 40%	2734
July	1st to 10th	Day	10% 6% 3 8% 6% 5% 5% 4 7% 8% 37%	4440
	11th to 20th	Day	7% 4 2 4 4 4 4 4 7% 10% 50%	4440
	21st to end	Day	7% 5% 2 6% 5% 5% 6% 4 7% 10% 44%	4697
August	1st to 10th	Day	11% 5% 2 7% 4 5% 6% 5% 6% 9% 41%	4104
	11th to 20th	Day	11% 6% 2 6% 5% 4 4 4 6% 7% 45%	4044
	21st to end	Day	8% 6% 2 7% 4 5% 5% 5% 7% 9% 42%	4449
September	1st to 10th	Day	10% 7% 2 8% 4 6% 5% 4 6% 8% 42%	2180
	11th to 20th	Day	11% 5% 2 5% 4 4 5% 4 5% 8% 47%	2090
	21st to end	Day	14% 7% 3 7% 5% 5% 5% 3 5% 8% 38%	2090
October	1st to 10th	Day	13% 7% 2 7% 5% 5% 5% 3 5% 6% 41%	2054
	11th to 20th	Day	19% 11% 3 6% 6% 5% 5% 3 5% 6% 31%	1900
	21st to end	Day	21% 9% 3 8% 5% 4 5% 5% 5% 8% 27%	1881
November	1st to 10th	Day	13% 10% 3 8% 5% 4 5% 4 5% 7% 35%	1699
	11th to 20th	Day	13% 13% 4 9% 6% 5% 6% 3 6% 7% 28%	1710
	21st to end	Day	18% 14% 5% 9% 6% 5% 5% 3 4 6% 25%	1596
December	1st to 10th	Day	14% 18% 6% 12% 8% 5% 5% 3 5% 4 21%	1481
	11th to 20th	Day	15% 17% 6% 10% 5% 4 4 4 5% 7% 24%	1675
	21st to end	Day	27% 20% 6% 12% 5% 4 4 3 4 5% 10%	2690
January	1st to 10th	Night	16% 16% 6% 12% 6% 5% 4 3 4 5% 22%	4428
	11th to 20th	Night	15% 16% 7% 18% 10% 8% 5% 3 4 4 13%	4440
	21st to end	Night	19% 19% 7% 11% 6% 5% 4 3 5% 5% 16%	4755
February	1st to 10th	Night	14% 14% 4 11% 7% 6% 5% 4 5% 6% 24%	2470
	11th to 20th	Night	14% 13% 5% 12% 7% 5% 4 4 5% 5% 27%	2261
	21st to end	Night	16% 14% 4 11% 6% 5% 4 3 5% 6% 27%	1884
March	1st to 10th	Night	14% 10% 4 7% 5% 4 3 3 4 6% 40%	3707
	11th to 20th	Night	10% 8% 3 6% 5% 5% 4 4 7% 8% 41%	3480
	21st to end	Night	16% 11% 5% 8% 4 4 4 3 5% 6% 33%	3817
April	1st to 10th	Night	17% 13% 3 6% 4 3 3 3 5% 7% 36%	1939
	11th to 20th	Night	19% 7% 2 6% 4 4 5% 3 5% 6% 38%	1734
	21st to end	Night	19% 8% 2 6% 4 4 5% 3 5% 7% 38%	1710
May	1st to 10th	Night	13% 8% 3 8% 5% 4 5% 4 6% 8% 38%	2813
	11th to 20th	Night	16% 7% 3 7% 4 3 4 3 4 8% 42%	2812
	21st to end	Night	12% 5% 2 5% 4 4 4 4 5% 7% 48%	2904
June	1st to 10th	Night	11% 7% 2 5% 5% 4 4 3 7% 7% 45%	1411
	11th to 20th	Night	11% 5% 2 5% 4 4 4 4 6% 9% 45%	1330
	21st to end	Night	8% 5% 2 5% 5% 4 5% 4 6% 8% 47%	1436
July	1st to 10th	Night	8% 5% 2 7% 4 4 5% 4 7% 9% 44%	2530
	11th to 20th	Night	8% 3 1 4 4 4 4 3 5% 8% 56%	2530
	21st to end	Night	6% 4 2 6% 5% 5% 6% 4 7% 8% 47%	2862
August	1st to 10th	Night	10% 6% 2 5% 3 4 4 4 6% 8% 48%	2825
	11th to 20th	Night	11% 5% 2 6% 4 4 4 4 5% 7% 48%	2785
	21st to end	Night	8% 5% 2 6% 4 4 5% 4 6% 7% 49%	3204
September	1st to 10th	Night	8% 6% 2 6% 5% 5% 5% 3 5% 6% 48%	1981
	11th to 20th	Night	11% 4 2 4 3 2 4 3 5% 7% 54%	2090
	21st to end	Night	15% 7% 3 6% 4 4 4 3 5% 8% 43%	2090
October	1st to 10th	Night	16% 6% 2 6% 3 3 3 3 5% 6% 45%	2125
	11th to 20th	Night	18% 10% 4 8% 5% 5% 4 3 5% 6% 33%	2280
	21st to end	Night	22% 10% 3 8% 4 5% 4 3 5% 6% 31%	2712
November	1st to 10th	Night	14% 10% 3 6% 4 4 4 3 5% 6% 42%	2452
	11th to 20th	Night	15% 12% 3 8% 6% 5% 5% 5% 6% 7% 29%	2470
	21st to end	Night	19% 14% 4 9% 5% 5% 4 3 5% 6% 26%	2579
December	1st to 10th	Night	16% 18% 6% 11% 6% 5% 4 5% 4 5% 21%	2697
	11th to 20th	Night	14% 15% 5% 12% 6% 5% 5% 3 5% 6% 23%	3522
	21st to end	Night	27% 20% 6% 9% 5% 4 3 3 4 5% 15%	4971

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	66% 5% 13% 11% 4	2528
	11th to 20th	Day	79% 5% 7% 6% 3	2530
	21st to end	Day	76% 4 8% 8% 4	2907
February	1st to 10th	Day	61% 7% 10% 16% 6%	1710
	11th to 20th	Day	61% 4 10% 16% 8% 1	1810
	21st to end	Day	57% 7% 11% 16% 7% 1	1570
March	1st to 10th	Day	53% 4 12% 22% 7% 1	3144
	11th to 20th	Day	53% 6% 11% 19% 9% 2	3480
	21st to end	Day	56% 5% 12% 16% 10% 2	3815
April	1st to 10th	Day	54% 5% 10% 19% 11%	2256
	11th to 20th	Day	47% 5% 11% 21% 14% 2	2394
	21st to end	Day	50% 5% 12% 19% 13% 2	2470
May	1st to 10th	Day	44% 7% 12% 21% 15% 2	4120
	11th to 20th	Day	42% 6% 14% 25% 12% 1	4085
	21st to end	Day	36% 5% 11% 21% 22% 4	4667
June	1st to 10th	Day	38% 6% 12% 28% 14% 2	2760
	11th to 20th	Day	37% 5% 12% 25% 18% 2	2850
	21st to end	Day	37% 7% 14% 25% 15% 1	2734
July	1st to 10th	Day	41% 8% 12% 21% 15% 2	4371
	11th to 20th	Day	27% 6% 15% 36% 15% 1	4365
	21st to end	Day	34% 7% 15% 21% 21% 2	4548
August	1st to 10th	Day	38% 6% 13% 26% 16% 1	4091
	11th to 20th	Day	36% 6% 12% 34% 11% 1	4083
	21st to end	Day	37% 6% 15% 28% 13% 1	4448
September	1st to 10th	Day	40% 6% 14% 26% 13% 2	2180
	11th to 20th	Day	34% 5% 13% 31% 16% 1	2090
	21st to end	Day	44% 4 14% 25% 13%	2090
October	1st to 10th	Day	33% 4 9% 33% 18% 2	3418
	11th to 20th	Day	42% 4 13% 28% 14%	3140
	21st to end	Day	50% 5% 13% 24% 8% 1	3081
November	1st to 10th	Day	47% 7% 12% 22% 11% 1	1699
	11th to 20th	Day	54% 5% 14% 18% 9%	1710
	21st to end	Day	60% 5% 15% 15% 5% 1	1596
December	1st to 10th	Day	66% 5% 11% 14% 3	1481
	11th to 20th	Day	61% 4 13% 17% 4 1	1671
	21st to end	Day	77% 4 9% 7% 3	2690
January	1st to 10th	Night	63% 5% 12% 13% 6% 1	4428
	11th to 20th	Night	76% 4 7% 9% 4	4440
	21st to end	Night	70% 5% 11% 11% 3	4755
February	1st to 10th	Night	60% 6% 8% 18% 7% 1	2470
	11th to 20th	Night	59% 5% 8% 19% 8% 1	2262
	21st to end	Night	59% 4 10% 17% 9% 1	1884
March	1st to 10th	Night	46% 4 14% 27% 8% 1	3707
	11th to 20th	Night	39% 5% 16% 22% 16% 1	3480
	21st to end	Night	51% 5% 12% 21% 10% 1	3817
April	1st to 10th	Night	48% 4 9% 22% 14% 2	1939
	11th to 20th	Night	46% 5% 9% 20% 17% 2	1734
	21st to end	Night	46% 6% 10% 21% 15% 3	1710
May	1st to 10th	Night	44% 5% 12% 20% 15% 4	2840
	11th to 20th	Night	42% 5% 10% 28% 13% 3	2813
	21st to end	Night	36% 5% 10% 22% 20% 6%	2912
June	1st to 10th	Night	37% 5% 11% 25% 20% 2	1411
	11th to 20th	Night	35% 5% 13% 22% 22% 2	1330
	21st to end	Night	34% 6% 12% 27% 18% 2	1436
July	1st to 10th	Night	34% 6% 12% 26% 15% 7%	2490
	11th to 20th	Night	27% 4 13% 35% 19% 1	2482
	21st to end	Night	33% 7% 17% 22% 19% 2	2771
August	1st to 10th	Night	33% 6% 13% 30% 16% 1	2814
	11th to 20th	Night	34% 5% 14% 31% 14% 1	2812
	21st to end	Night	33% 6% 12% 32% 15% 1	3204
September	1st to 10th	Night	36% 6% 11% 28% 18% 1	1981
	11th to 20th	Night	29% 6% 12% 32% 19% 1	2090
	21st to end	Night	41% 5% 13% 28% 12% 1	2090
October	1st to 10th	Night	27% 4 10% 34% 24% 1	3541
	11th to 20th	Night	45% 4 10% 25% 16%	3779
	21st to end	Night	44% 4 10% 30% 11%	4462
November	1st to 10th	Night	43% 6% 11% 26% 14% 1	2452
	11th to 20th	Night	53% 6% 13% 20% 8% 1	2470
	21st to end	Night	58% 4 15% 16% 5% 1	2579
December	1st to 10th	Night	64% 4 11% 15% 5%	2697
	11th to 20th	Night	60% 6% 13% 13% 7% 1	3525
	21st to end	Night	73% 5% 11% 8% 4	4971

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	21% 11% 37% 20% 9% 2	270
	11th to 20th	Day	24% 13% 37% 20% 7%	270
	21st to end	Day	25% 13% 31% 25% 6%	297
February	1st to 10th	Day	22% 20% 34% 19% 3 1	270
	11th to 20th	Day	20% 15% 36% 25% 4	270
	21st to end	Day	24% 25% 34% 12% 4	225
March	1st to 10th	Day	23% 15% 40% 17% 5% 1	281
	11th to 20th	Day	21% 12% 30% 25% 10% 1	460
	21st to end	Day	28% 9% 30% 24% 8% 1	506
April	1st to 10th	Day	21% 14% 32% 24% 9% 1	460
	11th to 20th	Day	22% 17% 29% 21% 6% 5%	452
	21st to end	Day	21% 9% 32% 23% 13% 2	460
May	1st to 10th	Day	22% 11% 29% 22% 11% 4	463
	11th to 20th	Day	19% 8% 28% 23% 15% 7%	487
	21st to end	Day	14% 7% 23% 26% 21% 8%	629
June	1st to 10th	Day	13% 9% 27% 31% 13% 6%	680
	11th to 20th	Day	14% 8% 29% 28% 17% 5%	680
	21st to end	Day	13% 7% 26% 30% 17% 6%	680
July	1st to 10th	Day	8% 4 22% 31% 22% 13%	671
	11th to 20th	Day	12% 6% 23% 30% 19% 10%	668
	21st to end	Day	8% 4 25% 30% 25% 8%	672
August	1st to 10th	Day	11% 4 19% 25% 24% 17%	486
	11th to 20th	Day	12% 4 15% 25% 29% 14%	479
	21st to end	Day	13% 5% 19% 26% 25% 12%	539
September	1st to 10th	Day	12% 5% 25% 26% 21% 11%	490
	11th to 20th	Day	11% 5% 19% 22% 27% 17%	490
	21st to end	Day	18% 10% 21% 24% 18% 10%	490
October	1st to 10th	Day	16% 10% 29% 21% 17% 7%	490
	11th to 20th	Day	22% 14% 27% 28% 9% 1	490
	21st to end	Day	27% 13% 34% 19% 6% 2	330
November	1st to 10th	Day	16% 15% 34% 22% 10% 2	279
	11th to 20th	Day	19% 17% 40% 17% 5% 2	270
	21st to end	Day	25% 11% 38% 20% 6%	216
December	1st to 10th	Day	25% 16% 36% 16% 7% 1	180
	11th to 20th	Day	22% 18% 41% 15% 3 1	180
	21st to end	Day	28% 15% 35% 19% 3	272
January	1st to 10th	Night	22% 11% 35% 24% 7% 1	950
	11th to 20th	Night	25% 11% 32% 25% 6% 1	950
	21st to end	Night	20% 7% 32% 32% 8%	968
February	1st to 10th	Night	20% 11% 35% 28% 5%	760
	11th to 20th	Night	20% 12% 35% 27% 5%	743
	21st to end	Night	24% 12% 37% 23% 4	628
March	1st to 10th	Night	21% 8% 33% 30% 8%	760
	11th to 20th	Night	17% 12% 35% 29% 7% 1	760
	21st to end	Night	24% 9% 30% 30% 7% 1	836
April	1st to 10th	Night	22% 11% 34% 25% 7% 1	609
	11th to 20th	Night	24% 7% 33% 25% 9% 1	563
	21st to end	Night	22% 8% 31% 31% 8% 1	570
May	1st to 10th	Night	18% 6% 33% 34% 9% 1	570
	11th to 20th	Night	20% 5% 26% 36% 11% 1	561
	21st to end	Night	14% 4 24% 36% 19% 3	617
June	1st to 10th	Night	13% 4 28% 41% 14%	461
	11th to 20th	Night	14% 4 25% 42% 14%	380
	21st to end	Night	9% 5% 23% 42% 20% 1	486
July	1st to 10th	Night	9% 2 17% 44% 26% 3	555
	11th to 20th	Night	10% 1 19% 41% 26% 3	552
	21st to end	Night	9% 2 17% 47% 23% 1	624
August	1st to 10th	Night	9% 2 14% 44% 29% 2	567
	11th to 20th	Night	8% 1 17% 40% 30% 4	564
	21st to end	Night	12% 4 19% 34% 29% 3	627
September	1st to 10th	Night	9% 5% 23% 35% 23% 5%	651
	11th to 20th	Night	14% 3 15% 36% 29% 4	760
	21st to end	Night	17% 6% 20% 33% 20% 4	760
October	1st to 10th	Night	19% 7% 24% 32% 16% 2	760
	11th to 20th	Night	24% 10% 26% 30% 9%	760
	21st to end	Night	25% 9% 32% 27% 6%	836
November	1st to 10th	Night	20% 10% 30% 29% 10%	755
	11th to 20th	Night	19% 13% 36% 24% 8% 1	760
	21st to end	Night	26% 9% 36% 24% 5%	760
December	1st to 10th	Night	26% 11% 32% 25% 5% 1	797
	11th to 20th	Night	22% 10% 38% 25% 5%	950
	21st to end	Night	32% 10% 32% 23% 3	1045

Page generated at 2024-11-01 22:47:37. Version ac07

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