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 2024-04-10.

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	14% 10% 4 7% 6% 4 5% 5% 5% 7% 33%	82766
	Night	15% 10% 4 7% 6% 3 4 4 5% 6% 33%	86028
Transparency	Day	50% 6% 12% 20% 11% 1	82471
	Night	51% 5% 12% 20% 11% 1	85844
Seeing	Day	17% 10% 28% 24% 15% 6%	14652
	Night	19% 8% 29% 31% 12% 1	24592

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% 10% 8% 3 5% 4 4 4 21%	2527
	11th to 20th	Day	14% 18% 8% 14% 14% 7% 5% 4 3 4 8%	2530
	21st to end	Day	23% 21% 8% 10% 6% 4 4 4 3 5% 12%	2907
February	1st to 10th	Day	11% 15% 5% 11% 8% 5% 6% 5% 5% 6% 22%	1710
	11th to 20th	Day	13% 13% 6% 10% 8% 5% 6% 4 4 5% 25%	1800
	21st to end	Day	14% 12% 6% 10% 8% 3 5% 4 5% 6% 27%	1570
March	1st to 10th	Day	17% 12% 3 7% 6% 4 4 4 5% 7% 31%	3144
	11th to 20th	Day	12% 12% 6% 8% 7% 4 5% 5% 4 6% 31%	3480
	21st to end	Day	18% 12% 5% 7% 6% 3 5% 5% 5% 6% 29%	3815
April	1st to 10th	Day	19% 11% 5% 6% 5% 3 5% 4 5% 6% 30%	2245
	11th to 20th	Day	17% 9% 3 6% 5% 3 4 4 6% 7% 35%	2266
	21st to end	Day	18% 8% 4 7% 6% 3 5% 5% 4 6% 34%	2340
May	1st to 10th	Day	17% 8% 3 5% 5% 3 5% 6% 5% 8% 36%	2340
	11th to 20th	Day	17% 7% 4 6% 5% 3 4 4 5% 6% 39%	2301
	21st to end	Day	12% 6% 3 6% 5% 3 6% 5% 7% 8% 41%	2625
June	1st to 10th	Day	11% 6% 3 6% 5% 3 5% 5% 7% 8% 43%	2614
	11th to 20th	Day	12% 5% 2 5% 6% 3 5% 4 6% 9% 44%	2700
	21st to end	Day	10% 5% 2 5% 5% 4 6% 6% 8% 9% 40%	2591
July	1st to 10th	Day	5% 3 2 5% 5% 3 5% 5% 8% 10% 49%	2520
	11th to 20th	Day	10% 4 2 4 5% 3 5% 5% 6% 8% 48%	2520
	21st to end	Day	8% 4 2 5% 6% 3 6% 5% 7% 9% 45%	2680
August	1st to 10th	Day	10% 5% 2 6% 5% 4 5% 6% 6% 10% 42%	2327
	11th to 20th	Day	9% 5% 3 5% 6% 3 5% 5% 6% 7% 44%	2303
	21st to end	Day	10% 6% 2 5% 4 3 5% 5% 6% 8% 44%	2533
September	1st to 10th	Day	11% 6% 3 7% 6% 4 6% 5% 6% 8% 40%	2066
	11th to 20th	Day	12% 5% 3 4 4 3 5% 5% 5% 9% 45%	1980
	21st to end	Day	14% 6% 3 6% 6% 3 5% 5% 5% 8% 39%	1980
October	1st to 10th	Day	14% 6% 3 6% 6% 4 5% 4 5% 6% 40%	1946
	11th to 20th	Day	20% 11% 3 5% 7% 4 5% 4 5% 6% 29%	1800
	21st to end	Day	22% 9% 4 8% 5% 3 5% 5% 5% 7% 27%	1782
November	1st to 10th	Day	13% 10% 3 7% 6% 3 5% 5% 5% 7% 36%	1672
	11th to 20th	Day	14% 12% 4 8% 6% 3 6% 5% 6% 7% 28%	1710
	21st to end	Day	18% 13% 6% 8% 6% 4 5% 4 4 7% 25%	1596
December	1st to 10th	Day	14% 17% 7% 11% 8% 4 5% 4 5% 4 21%	1481
	11th to 20th	Day	15% 16% 6% 9% 6% 3 5% 4 4 7% 24%	1675
	21st to end	Day	27% 19% 7% 11% 6% 3 4 4 4 5% 10%	2690
January	1st to 10th	Night	16% 16% 7% 10% 8% 4 4 4 4 5% 22%	4428
	11th to 20th	Night	15% 15% 7% 15% 12% 6% 5% 3 4 4 13%	4440
	21st to end	Night	19% 18% 8% 10% 7% 4 4 4 5% 5% 16%	4755
February	1st to 10th	Night	14% 13% 5% 10% 8% 4 5% 5% 5% 6% 24%	2470
	11th to 20th	Night	14% 12% 5% 11% 8% 4 5% 5% 4 6% 27%	2261
	21st to end	Night	17% 13% 5% 9% 7% 4 4 4 4 6% 27%	1884
March	1st to 10th	Night	15% 10% 4 7% 5% 3 3 3 4 6% 40%	3707
	11th to 20th	Night	10% 8% 3 5% 6% 4 4 4 7% 8% 41%	3480
	21st to end	Night	16% 10% 6% 7% 5% 3 5% 4 5% 6% 33%	3817
April	1st to 10th	Night	18% 11% 4 6% 5% 2 4 4 4 7% 36%	1939
	11th to 20th	Night	19% 6% 3 5% 5% 3 5% 4 5% 7% 38%	1642
	21st to end	Night	19% 8% 3 5% 4 3 5% 4 5% 7% 38%	1620
May	1st to 10th	Night	15% 8% 3 7% 6% 3 6% 5% 5% 7% 34%	1620
	11th to 20th	Night	18% 6% 3 5% 5% 2 4 4 5% 8% 40%	1592
	21st to end	Night	12% 3 2 5% 5% 3 5% 6% 5% 7% 46%	1647
June	1st to 10th	Night	11% 6% 3 4 5% 3 5% 4 7% 7% 46%	1337
	11th to 20th	Night	12% 5% 2 4 4 3 4 5% 6% 9% 45%	1260
	21st to end	Night	7% 5% 2 5% 6% 3 6% 5% 5% 9% 48%	1360
July	1st to 10th	Night	6% 3 2 5% 4 3 4 5% 5% 8% 55%	1440
	11th to 20th	Night	8% 4 2 4 4 3 5% 4 6% 9% 50%	1440
	21st to end	Night	7% 4 2 5% 5% 3 4 5% 6% 8% 51%	1637
August	1st to 10th	Night	9% 4 1 3 5% 2 4 6% 7% 9% 49%	1611
	11th to 20th	Night	7% 3 2 5% 5% 3 5% 5% 5% 8% 52%	1598
	21st to end	Night	10% 5% 2 4 4 3 4 4 5% 7% 52%	1820
September	1st to 10th	Night	9% 5% 3 6% 6% 3 5% 5% 5% 6% 47%	1876
	11th to 20th	Night	11% 4 2 4 4 2 4 4 5% 7% 52%	1980
	21st to end	Night	15% 6% 3 5% 5% 3 4 3 5% 8% 44%	1980
October	1st to 10th	Night	17% 6% 2 5% 4 2 4 4 5% 6% 44%	2013
	11th to 20th	Night	19% 9% 4 7% 6% 4 4 4 5% 6% 32%	2160
	21st to end	Night	23% 9% 3 8% 5% 4 4 4 4 6% 30%	2569
November	1st to 10th	Night	14% 9% 3 5% 5% 3 4 4 5% 7% 42%	2406
	11th to 20th	Night	15% 11% 4 7% 7% 4 5% 6% 6% 7% 29%	2470
	21st to end	Night	19% 12% 5% 7% 6% 3 5% 4 5% 6% 26%	2579
December	1st to 10th	Night	17% 15% 7% 10% 7% 4 5% 6% 4 5% 21%	2697
	11th to 20th	Night	14% 14% 6% 11% 7% 4 5% 5% 5% 6% 23%	3522
	21st to end	Night	27% 19% 6% 8% 5% 3 3 4 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	55% 5% 11% 18% 11%	2245
	11th to 20th	Day	48% 5% 12% 20% 14% 2	2266
	21st to end	Day	50% 5% 13% 18% 12% 2	2340
May	1st to 10th	Day	45% 6% 12% 23% 11% 2	2340
	11th to 20th	Day	45% 6% 11% 21% 15% 2	2305
	21st to end	Day	40% 6% 14% 24% 15% 2	2625
June	1st to 10th	Day	37% 6% 13% 28% 14% 2	2614
	11th to 20th	Day	38% 5% 12% 24% 18% 2	2700
	21st to end	Day	37% 7% 14% 25% 16% 2	2591
July	1st to 10th	Day	29% 7% 12% 29% 20% 3	2451
	11th to 20th	Day	32% 7% 13% 28% 18% 2	2445
	21st to end	Day	34% 7% 13% 24% 19% 3	2531
August	1st to 10th	Day	36% 7% 14% 28% 13% 2	2314
	11th to 20th	Day	37% 7% 14% 27% 14% 2	2303
	21st to end	Day	36% 6% 13% 28% 15% 2	2533
September	1st to 10th	Day	41% 6% 14% 24% 12% 2	2066
	11th to 20th	Day	35% 6% 13% 31% 14%	1980
	21st to end	Day	43% 4 14% 25% 13%	1980
October	1st to 10th	Day	44% 5% 10% 25% 14% 1	1946
	11th to 20th	Day	56% 4 12% 20% 8%	1800
	21st to end	Day	56% 6% 14% 17% 7% 1	1782
November	1st to 10th	Day	47% 7% 12% 22% 12% 1	1672
	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	49% 4 10% 22% 14% 2	1939
	11th to 20th	Night	45% 5% 10% 20% 17% 3	1642
	21st to end	Night	45% 5% 10% 21% 16% 3	1620
May	1st to 10th	Night	48% 5% 11% 20% 14% 2	1620
	11th to 20th	Night	44% 5% 10% 21% 17% 4	1593
	21st to end	Night	37% 7% 11% 26% 15% 4	1648
June	1st to 10th	Night	37% 5% 11% 25% 20% 2	1337
	11th to 20th	Night	35% 6% 13% 23% 21% 2	1260
	21st to end	Night	33% 6% 13% 27% 18% 2	1360
July	1st to 10th	Night	26% 7% 11% 31% 21% 5%	1400
	11th to 20th	Night	29% 5% 15% 28% 21% 2	1392
	21st to end	Night	29% 7% 15% 27% 19% 3	1546
August	1st to 10th	Night	28% 7% 16% 33% 15% 1	1600
	11th to 20th	Night	30% 7% 14% 30% 17% 2	1598
	21st to end	Night	32% 5% 13% 30% 18% 1	1820
September	1st to 10th	Night	37% 6% 11% 26% 18% 1	1876
	11th to 20th	Night	31% 6% 13% 33% 18% 1	1980
	21st to end	Night	40% 5% 13% 29% 12% 1	1980
October	1st to 10th	Night	40% 6% 10% 27% 15% 1	2013
	11th to 20th	Night	53% 5% 10% 22% 9% 1	2160
	21st to end	Night	55% 4 11% 20% 9%	2569
November	1st to 10th	Night	43% 6% 11% 26% 14% 1	2406
	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	457
	11th to 20th	Day	22% 17% 27% 21% 7% 5%	412
	21st to end	Day	20% 9% 32% 23% 14% 2	420
May	1st to 10th	Day	23% 11% 30% 21% 12% 4	423
	11th to 20th	Day	20% 8% 30% 21% 14% 7%	447
	21st to end	Day	15% 7% 23% 26% 21% 9%	579
June	1st to 10th	Day	13% 9% 27% 32% 13% 6%	630
	11th to 20th	Day	14% 8% 27% 28% 18% 5%	630
	21st to end	Day	13% 6% 26% 31% 18% 6%	630
July	1st to 10th	Day	7% 4 22% 31% 23% 14%	621
	11th to 20th	Day	12% 5% 24% 29% 19% 10%	618
	21st to end	Day	8% 4 25% 31% 24% 8%	621
August	1st to 10th	Day	11% 3 18% 25% 24% 19%	446
	11th to 20th	Day	12% 4 15% 25% 30% 15%	439
	21st to end	Day	14% 5% 19% 25% 26% 13%	495
September	1st to 10th	Day	13% 5% 23% 28% 20% 11%	450
	11th to 20th	Day	12% 5% 19% 22% 26% 16%	450
	21st to end	Day	17% 10% 20% 24% 18% 11%	450
October	1st to 10th	Day	16% 9% 29% 20% 18% 8%	450
	11th to 20th	Day	23% 14% 26% 27% 8% 1	450
	21st to end	Day	28% 12% 34% 18% 7% 2	297
November	1st to 10th	Day	17% 15% 34% 22% 10% 2	270
	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	23% 7% 32% 26% 10% 1	533
	21st to end	Night	22% 8% 30% 32% 8% 1	540
May	1st to 10th	Night	19% 5% 33% 34% 9% 1	540
	11th to 20th	Night	21% 5% 26% 36% 11% 1	531
	21st to end	Night	14% 4 24% 36% 19% 3	584
June	1st to 10th	Night	13% 5% 27% 41% 14%	437
	11th to 20th	Night	14% 4 24% 43% 15%	360
	21st to end	Night	8% 4 22% 44% 21% 1	460
July	1st to 10th	Night	8% 2 16% 44% 27% 3	525
	11th to 20th	Night	10% 1 18% 41% 27% 3	522
	21st to end	Night	9% 2 18% 47% 23% 2	591
August	1st to 10th	Night	9% 2 13% 45% 29% 2	537
	11th to 20th	Night	8% 1 17% 39% 30% 4	534
	21st to end	Night	12% 4 19% 34% 29% 3	594
September	1st to 10th	Night	10% 4 22% 36% 23% 5%	616
	11th to 20th	Night	14% 3 16% 35% 28% 4	720
	21st to end	Night	17% 5% 20% 33% 21% 4	720
October	1st to 10th	Night	20% 7% 23% 32% 17% 2	720
	11th to 20th	Night	24% 11% 27% 30% 8%	720
	21st to end	Night	27% 9% 31% 27% 5% 1	792
November	1st to 10th	Night	19% 10% 30% 29% 11%	740
	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 2024-04-07 09:28:17. Version ac07

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