Springfield
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Springfield clear sky chart from 2005-11-06 to 2024-04-25.

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% 7% 3 5% 5% 3 4 4 5% 7% 44%	83492
	Night	12% 7% 3 5% 4 2 4 4 5% 7% 47%	85647
Transparency	Day	39% 6% 11% 24% 16% 3	83215
	Night	37% 6% 11% 24% 18% 3	85444
Seeing	Day	15% 10% 26% 27% 17% 5%	14711
	Night	15% 11% 31% 30% 12% 1	24725

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% 11% 4 4 5% 2 3 3 3 5% 45%	2847
	11th to 20th	Day	10% 10% 4 6% 6% 3 5% 3 4 5% 42%	2850
	21st to end	Day	21% 10% 5% 6% 3 2 3 3 4 5% 38%	3135
February	1st to 10th	Day	15% 11% 4 7% 6% 3 4 4 5% 5% 36%	1710
	11th to 20th	Day	14% 8% 5% 7% 5% 2 4 4 4 6% 43%	1687
	21st to end	Day	16% 9% 3 5% 5% 4 5% 4 4 7% 38%	1641
March	1st to 10th	Day	16% 8% 4 5% 4 2 3 3 3 5% 47%	3436
	11th to 20th	Day	13% 7% 3 4 4 2 3 3 4 7% 51%	3480
	21st to end	Day	16% 10% 4 6% 6% 4 5% 4 5% 6% 34%	3814
April	1st to 10th	Day	11% 8% 3 6% 4 2 4 5% 5% 6% 45%	2251
	11th to 20th	Day	16% 9% 3 5% 5% 3 4 5% 5% 6% 40%	2254
	21st to end	Day	20% 7% 3 6% 5% 4 4 4 4 7% 36%	2209
May	1st to 10th	Day	19% 8% 2 5% 4 3 6% 4 4 7% 37%	2299
	11th to 20th	Day	15% 5% 2 5% 6% 4 5% 4 5% 7% 42%	2302
	21st to end	Day	12% 6% 3 5% 6% 5% 6% 6% 8% 9% 35%	2616
June	1st to 10th	Day	9% 4 2 5% 5% 2 5% 5% 5% 10% 47%	2520
	11th to 20th	Day	7% 4 2 4 5% 4 6% 6% 6% 10% 47%	2520
	21st to end	Day	5% 2 2 4 4 3 5% 5% 7% 9% 54%	2520
July	1st to 10th	Day	9% 5% 2 5% 5% 4 6% 6% 8% 11% 39%	2347
	11th to 20th	Day	5% 3 2 4 5% 3 6% 6% 7% 10% 49%	2340
	21st to end	Day	9% 5% 3 5% 5% 3 5% 5% 7% 11% 41%	2546
August	1st to 10th	Day	8% 5% 3 5% 6% 4 5% 6% 7% 9% 41%	2328
	11th to 20th	Day	9% 5% 2 5% 6% 4 5% 6% 8% 8% 43%	2243
	21st to end	Day	7% 4 2 5% 5% 3 5% 4 6% 9% 50%	2376
September	1st to 10th	Day	11% 5% 2 4 4 3 5% 4 4 7% 49%	2160
	11th to 20th	Day	11% 5% 3 5% 5% 3 5% 4 4 7% 47%	2101
	21st to end	Day	7% 4 2 4 4 3 5% 5% 6% 7% 53%	1908
October	1st to 10th	Day	11% 4 2 4 4 2 4 4 5% 7% 55%	1800
	11th to 20th	Day	14% 7% 2 5% 4 2 3 3 3 5% 53%	1800
	21st to end	Day	19% 6% 2 5% 4 2 3 2 4 5% 47%	1980
November	1st to 10th	Day	12% 5% 2 3 3 2 3 3 4 5% 58%	1858
	11th to 20th	Day	14% 7% 3 4 4 2 3 4 4 6% 49%	1763
	21st to end	Day	15% 8% 3 5% 4 2 3 2 3 6% 48%	1520
December	1st to 10th	Day	12% 10% 3 6% 5% 3 4 3 4 7% 43%	1520
	11th to 20th	Day	13% 11% 3 7% 5% 3 4 3 3 5% 42%	1918
	21st to end	Day	14% 16% 7% 8% 6% 3 4 4 4 5% 28%	2893
January	1st to 10th	Night	12% 10% 4 8% 6% 3 4 4 3 5% 42%	4108
	11th to 20th	Night	11% 6% 3 7% 9% 3 5% 5% 5% 5% 42%	4120
	21st to end	Night	20% 12% 6% 6% 3 1 3 3 3 4 39%	4532
February	1st to 10th	Night	14% 9% 4 6% 5% 2 4 4 4 6% 43%	2470
	11th to 20th	Night	15% 7% 3 6% 5% 2 3 3 4 6% 45%	2380
	21st to end	Night	14% 8% 4 5% 5% 2 4 3 5% 5% 44%	1827
March	1st to 10th	Night	16% 9% 3 5% 4 2 3 2 4 5% 47%	3419
	11th to 20th	Night	13% 6% 2 4 4 2 4 4 4 6% 51%	3480
	21st to end	Night	13% 8% 4 6% 6% 3 5% 5% 5% 7% 38%	3817
April	1st to 10th	Night	10% 5% 2 4 4 3 3 4 5% 8% 52%	1929
	11th to 20th	Night	12% 8% 3 5% 4 3 3 3 5% 7% 47%	1875
	21st to end	Night	19% 6% 3 5% 5% 2 3 5% 6% 7% 39%	1850
May	1st to 10th	Night	15% 5% 3 4 4 3 4 4 5% 6% 47%	1656
	11th to 20th	Night	14% 5% 2 5% 4 2 3 5% 5% 7% 48%	1593
	21st to end	Night	11% 5% 3 5% 6% 3 5% 5% 7% 11% 39%	1655
June	1st to 10th	Night	7% 3 2 4 4 2 4 5% 6% 9% 53%	1440
	11th to 20th	Night	5% 4 2 4 4 3 4 5% 7% 10% 54%	1440
	21st to end	Night	3 2 2 2 3 3 3 3 5% 9% 66%	1440
July	1st to 10th	Night	8% 3 1 3 4 3 5% 5% 8% 9% 51%	1607
	11th to 20th	Night	4 2 1 3 3 2 4 4 6% 10% 60%	1620
	21st to end	Night	6% 4 2 4 4 4 5% 5% 7% 9% 51%	1772
August	1st to 10th	Night	6% 3 1 4 5% 3 4 5% 6% 10% 52%	1611
	11th to 20th	Night	7% 3 2 3 3 2 4 4 6% 8% 57%	1655
	21st to end	Night	5% 3 2 3 5% 3 4 5% 5% 10% 56%	1980
September	1st to 10th	Night	9% 4 2 4 5% 3 3 3 4 8% 55%	1800
	11th to 20th	Night	9% 5% 2 5% 4 2 4 4 5% 8% 52%	1855
	21st to end	Night	9% 4 2 4 3 2 3 3 4 6% 59%	2034
October	1st to 10th	Night	8% 4 2 3 3 3 3 4 5% 7% 60%	2160
	11th to 20th	Night	13% 6% 2 3 3 2 3 3 4 5% 55%	2160
	21st to end	Night	17% 8% 2 4 3 2 3 3 4 5% 49%	2376
November	1st to 10th	Night	12% 5% 2 3 3 2 2 3 3 6% 59%	2220
	11th to 20th	Night	11% 7% 2 5% 4 2 3 3 4 6% 53%	2411
	21st to end	Night	14% 8% 3 5% 4 2 3 4 4 5% 48%	2660
December	1st to 10th	Night	15% 9% 3 6% 3 2 3 4 5% 7% 42%	2660
	11th to 20th	Night	14% 9% 5% 8% 4 3 3 3 4 5% 42%	3279
	21st to end	Night	17% 17% 6% 7% 5% 2 4 3 4 5% 30%	4756

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	44% 4 7% 26% 17% 1	2848
	11th to 20th	Day	43% 5% 9% 27% 12% 3	2850
	21st to end	Day	49% 4 9% 17% 16% 4	3135
February	1st to 10th	Day	50% 5% 10% 22% 12% 2	1710
	11th to 20th	Day	45% 4 10% 21% 16% 4	1696
	21st to end	Day	47% 4 7% 20% 15% 7%	1641
March	1st to 10th	Day	40% 5% 8% 20% 19% 8%	3436
	11th to 20th	Day	35% 5% 10% 28% 15% 7%	3480
	21st to end	Day	49% 8% 12% 21% 9% 1	3814
April	1st to 10th	Day	39% 7% 12% 22% 19% 2	2251
	11th to 20th	Day	44% 6% 13% 18% 15% 3	2254
	21st to end	Day	50% 6% 9% 23% 11% 1	2209
May	1st to 10th	Day	48% 6% 12% 20% 13% 1	2299
	11th to 20th	Day	41% 8% 14% 24% 13% 1	2306
	21st to end	Day	42% 12% 13% 22% 11%	2616
June	1st to 10th	Day	32% 8% 15% 28% 15% 1	2520
	11th to 20th	Day	31% 8% 15% 30% 13% 2	2520
	21st to end	Day	24% 9% 16% 30% 16% 4	2520
July	1st to 10th	Day	35% 10% 17% 22% 13% 2	2283
	11th to 20th	Day	27% 10% 15% 27% 19% 3	2271
	21st to end	Day	35% 8% 15% 30% 10% 1	2405
August	1st to 10th	Day	35% 11% 18% 23% 14%	2314
	11th to 20th	Day	36% 8% 14% 28% 14% 1	2243
	21st to end	Day	31% 8% 13% 23% 20% 6%	2376
September	1st to 10th	Day	35% 6% 13% 25% 14% 7%	2160
	11th to 20th	Day	37% 5% 9% 22% 25% 2	2101
	21st to end	Day	29% 7% 10% 26% 24% 4	1908
October	1st to 10th	Day	30% 5% 11% 25% 24% 5%	1800
	11th to 20th	Day	35% 4 7% 26% 22% 6%	1800
	21st to end	Day	40% 4 9% 25% 17% 6%	1980
November	1st to 10th	Day	30% 5% 9% 28% 22% 5%	1858
	11th to 20th	Day	36% 4 8% 21% 24% 6%	1763
	21st to end	Day	40% 4 9% 23% 21% 2	1520
December	1st to 10th	Day	42% 4 9% 29% 14% 2	1520
	11th to 20th	Day	45% 5% 7% 18% 23% 2	1915
	21st to end	Day	57% 6% 8% 16% 11% 1	2893
January	1st to 10th	Night	46% 4 10% 23% 15% 2	4108
	11th to 20th	Night	43% 6% 11% 25% 13% 2	4120
	21st to end	Night	50% 4 9% 20% 15% 2	4532
February	1st to 10th	Night	43% 5% 11% 23% 14% 3	2470
	11th to 20th	Night	42% 4 10% 22% 18% 4	2381
	21st to end	Night	43% 4 10% 21% 17% 6%	1827
March	1st to 10th	Night	41% 6% 9% 19% 19% 6%	3419
	11th to 20th	Night	35% 7% 10% 25% 21% 3	3480
	21st to end	Night	44% 8% 14% 23% 10% 1	3817
April	1st to 10th	Night	31% 6% 11% 25% 22% 5%	1929
	11th to 20th	Night	36% 6% 12% 22% 19% 5%	1875
	21st to end	Night	44% 6% 12% 22% 15% 1	1850
May	1st to 10th	Night	39% 6% 12% 25% 17% 2	1656
	11th to 20th	Night	35% 8% 14% 25% 15% 2	1594
	21st to end	Night	38% 10% 16% 24% 11% 1	1656
June	1st to 10th	Night	26% 7% 16% 30% 18% 2	1440
	11th to 20th	Night	23% 8% 15% 30% 20% 3	1440
	21st to end	Night	17% 5% 19% 32% 20% 6%	1440
July	1st to 10th	Night	27% 9% 18% 27% 17% 3	1562
	11th to 20th	Night	19% 7% 16% 30% 27% 2	1566
	21st to end	Night	26% 8% 15% 35% 15% 1	1673
August	1st to 10th	Night	26% 8% 16% 34% 14% 1	1601
	11th to 20th	Night	25% 6% 14% 30% 23% 1	1655
	21st to end	Night	24% 7% 15% 26% 22% 7%	1980
September	1st to 10th	Night	28% 5% 14% 27% 19% 6%	1800
	11th to 20th	Night	30% 6% 11% 24% 26% 4	1855
	21st to end	Night	27% 5% 10% 25% 30% 4	2034
October	1st to 10th	Night	25% 6% 11% 26% 27% 6%	2160
	11th to 20th	Night	32% 4 8% 24% 25% 6%	2160
	21st to end	Night	38% 4 8% 22% 22% 7%	2376
November	1st to 10th	Night	28% 4 10% 26% 24% 7%	2220
	11th to 20th	Night	33% 4 7% 25% 25% 6%	2411
	21st to end	Night	39% 4 8% 24% 22% 3	2660
December	1st to 10th	Night	42% 5% 11% 23% 18% 2	2660
	11th to 20th	Night	46% 4 7% 21% 20% 2	3281
	21st to end	Night	56% 6% 10% 16% 9% 2	4756

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% 19% 39% 18% 3	270
	11th to 20th	Day	25% 23% 37% 14% 1	270
	21st to end	Day	19% 20% 43% 15% 3	297
February	1st to 10th	Day	21% 19% 43% 15% 2	270
	11th to 20th	Day	24% 26% 31% 16% 2	270
	21st to end	Day	28% 24% 36% 10% 1	225
March	1st to 10th	Day	22% 23% 34% 20% 2	270
	11th to 20th	Day	26% 17% 34% 20% 3	270
	21st to end	Day	27% 21% 39% 10% 2 1	297
April	1st to 10th	Day	21% 16% 39% 20% 4	431
	11th to 20th	Day	22% 17% 37% 18% 5%	452
	21st to end	Day	24% 17% 32% 21% 6% 1	437
May	1st to 10th	Day	22% 12% 31% 26% 8% 1	562
	11th to 20th	Day	17% 10% 30% 27% 13% 3	625
	21st to end	Day	13% 7% 31% 26% 16% 6%	679
June	1st to 10th	Day	10% 3 19% 31% 29% 9%	630
	11th to 20th	Day	7% 3 18% 37% 29% 5%	630
	21st to end	Day	6% 3 28% 36% 23% 5%	630
July	1st to 10th	Day	10% 3 14% 29% 32% 12%	621
	11th to 20th	Day	5% 4 14% 36% 33% 9%	618
	21st to end	Day	9% 2 11% 35% 30% 13%	684
August	1st to 10th	Day	9% 4 11% 40% 30% 5%	626
	11th to 20th	Day	10% 2 14% 35% 32% 7%	557
	21st to end	Day	11% 1 11% 28% 37% 12%	495
September	1st to 10th	Day	12% 1 10% 36% 30% 10%	450
	11th to 20th	Day	9% 2 17% 36% 26% 10%	391
	21st to end	Day	9% 4 25% 33% 23% 7%	270
October	1st to 10th	Day	11% 9% 27% 31% 17% 4	270
	11th to 20th	Day	15% 16% 36% 25% 7% 1	270
	21st to end	Day	29% 16% 27% 24% 3 1	297
November	1st to 10th	Day	14% 13% 38% 23% 10% 2	270
	11th to 20th	Day	16% 21% 30% 24% 7% 1	270
	21st to end	Day	22% 17% 34% 21% 5% 1	270
December	1st to 10th	Day	16% 14% 44% 17% 6% 3	270
	11th to 20th	Day	21% 17% 39% 19% 5%	270
	21st to end	Day	18% 27% 38% 14% 2	297
January	1st to 10th	Night	17% 19% 38% 22% 5%	950
	11th to 20th	Night	19% 19% 41% 17% 4	950
	21st to end	Night	17% 18% 42% 21% 2	1045
February	1st to 10th	Night	19% 16% 44% 19% 3	950
	11th to 20th	Night	21% 17% 41% 20% 2	906
	21st to end	Night	21% 22% 38% 17% 2	571
March	1st to 10th	Night	19% 16% 37% 24% 4	570
	11th to 20th	Night	22% 15% 34% 24% 5%	570
	21st to end	Night	21% 17% 36% 21% 4	627
April	1st to 10th	Night	14% 16% 39% 28% 4	570
	11th to 20th	Night	17% 13% 39% 26% 5%	563
	21st to end	Night	22% 11% 37% 23% 7%	555
May	1st to 10th	Night	16% 6% 37% 33% 9%	540
	11th to 20th	Night	15% 6% 29% 32% 17% 1	531
	21st to end	Night	12% 4 31% 31% 20% 2	584
June	1st to 10th	Night	7% 4 16% 43% 30% 1	540
	11th to 20th	Night	6% 2 23% 46% 22% 1	540
	21st to end	Night	2 1 23% 49% 24% 1	540
July	1st to 10th	Night	8% 1 10% 42% 35% 5%	525
	11th to 20th	Night	3 1 11% 44% 37% 4	522
	21st to end	Night	7% 1 8% 47% 34% 4	591
August	1st to 10th	Night	7% 2 9% 49% 30% 3	537
	11th to 20th	Night	8% 1 12% 50% 25% 3	534
	21st to end	Night	5% 1 12% 41% 37% 4	594
September	1st to 10th	Night	10% 2 14% 42% 30% 3	540
	11th to 20th	Night	11% 2 13% 43% 28% 3	540
	21st to end	Night	12% 4 21% 40% 21% 3	594
October	1st to 10th	Night	9% 5% 29% 33% 21% 3	720
	11th to 20th	Night	17% 8% 36% 30% 7%	720
	21st to end	Night	22% 11% 29% 28% 10%	792
November	1st to 10th	Night	14% 10% 39% 28% 10%	740
	11th to 20th	Night	15% 14% 38% 26% 7%	779
	21st to end	Night	20% 13% 36% 24% 7%	950
December	1st to 10th	Night	21% 13% 39% 23% 5%	950
	11th to 20th	Night	22% 14% 36% 25% 3	950
	21st to end	Night	20% 18% 40% 21% 2	1045

Page generated at 2024-04-22 08:25:42. Version ac07

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