Saint Paul
Clear Sky Chart
History

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

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 7% 5% 4 4 4 6% 7% 38%	101606
	Night	13% 9% 3 8% 5% 4 4 4 5% 6% 39%	97558
Transparency	Day	44% 7% 13% 24% 11% 1	105212
	Night	44% 6% 13% 24% 13% 1	102093
Seeing	Day	16% 12% 32% 26% 12% 3	16030
	Night	16% 10% 33% 31% 10% 1	25890

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	12% 16% 6% 18% 6% 5% 4 2 4 6% 20%	2527
	11th to 20th	Day	5% 13% 6% 13% 10% 8% 8% 7% 6% 4 20%	2534
	21st to end	Day	8% 20% 7% 12% 5% 4 5% 3 5% 6% 24%	3135
February	1st to 10th	Day	9% 11% 5% 10% 7% 6% 6% 5% 5% 6% 29%	1710
	11th to 20th	Day	8% 11% 6% 9% 6% 5% 5% 4 5% 7% 33%	1664
	21st to end	Day	12% 11% 4 11% 6% 5% 4 4 6% 8% 30%	1479
March	1st to 10th	Day	12% 10% 4 7% 5% 4 5% 3 5% 6% 40%	3344
	11th to 20th	Day	11% 9% 3 8% 5% 5% 4 3 5% 8% 40%	3480
	21st to end	Day	24% 12% 4 11% 5% 4 4 3 4 5% 24%	3867
April	1st to 10th	Day	16% 11% 3 7% 5% 4 4 3 5% 8% 34%	2280
	11th to 20th	Day	20% 10% 4 7% 4 4 4 3 5% 6% 32%	2254
	21st to end	Day	22% 12% 2 6% 4 4 5% 4 5% 6% 30%	2470
May	1st to 10th	Day	18% 7% 2 5% 4 4 4 3 6% 7% 40%	4270
	11th to 20th	Day	14% 6% 2 6% 4 4 4 3 6% 7% 45%	4399
	21st to end	Day	18% 7% 2 7% 5% 4 5% 4 5% 7% 36%	4824
June	1st to 10th	Day	12% 4 2 4 4 4 5% 4 6% 8% 47%	2660
	11th to 20th	Day	13% 6% 3 7% 5% 5% 4 5% 7% 9% 37%	2660
	21st to end	Day	11% 4 2 5% 5% 6% 5% 5% 8% 9% 40%	2660
July	1st to 10th	Day	11% 5% 2 6% 5% 5% 6% 5% 8% 9% 37%	4440
	11th to 20th	Day	7% 3 1 3 3 3 3 4 5% 8% 60%	4440
	21st to end	Day	7% 4 2 5% 4 4 5% 5% 7% 8% 48%	4782
August	1st to 10th	Day	13% 6% 2 5% 4 4 5% 4 6% 8% 43%	4104
	11th to 20th	Day	13% 5% 2 5% 4 4 5% 4 6% 8% 44%	4041
	21st to end	Day	11% 6% 2 6% 4 4 4 4 5% 7% 46%	4318
September	1st to 10th	Day	12% 6% 2 4 4 4 4 4 6% 6% 48%	2280
	11th to 20th	Day	13% 5% 2 5% 3 5% 5% 5% 6% 7% 46%	2263
	21st to end	Day	15% 6% 2 6% 4 3 4 3 6% 6% 44%	1990
October	1st to 10th	Day	17% 7% 2 5% 4 4 4 3 4 6% 44%	1900
	11th to 20th	Day	15% 10% 3 6% 5% 4 4 3 5% 7% 39%	1900
	21st to end	Day	17% 11% 4 7% 4 3 4 3 4 5% 38%	2057
November	1st to 10th	Day	13% 12% 3 9% 5% 4 4 4 5% 5% 36%	1613
	11th to 20th	Day	11% 14% 6% 11% 7% 5% 5% 2 6% 5% 28%	1520
	21st to end	Day	13% 11% 4 8% 5% 4 3 4 6% 7% 35%	1520
December	1st to 10th	Day	12% 13% 5% 12% 8% 5% 5% 3 5% 5% 25%	1520
	11th to 20th	Day	11% 14% 6% 11% 6% 5% 4 4 4 6% 28%	1918
	21st to end	Day	23% 16% 6% 16% 5% 4 3 2 3 5% 16%	2783
January	1st to 10th	Night	10% 16% 7% 15% 6% 4 4 3 4 4 27%	4428
	11th to 20th	Night	8% 11% 5% 14% 7% 6% 8% 7% 7% 6% 21%	4432
	21st to end	Night	11% 20% 7% 12% 5% 5% 3 3 4 4 26%	4532
February	1st to 10th	Night	7% 11% 5% 11% 7% 6% 4 4 5% 6% 35%	2470
	11th to 20th	Night	7% 10% 4 8% 6% 5% 5% 4 5% 7% 39%	2403
	21st to end	Night	12% 10% 3 8% 6% 5% 5% 3 5% 6% 37%	1975
March	1st to 10th	Night	9% 8% 2 7% 4 4 4 3 6% 6% 47%	3527
	11th to 20th	Night	9% 7% 3 8% 6% 6% 5% 4 6% 6% 40%	3480
	21st to end	Night	26% 12% 4 10% 4 3 2 2 4 5% 28%	3763
April	1st to 10th	Night	17% 11% 3 6% 4 4 4 3 5% 7% 37%	1900
	11th to 20th	Night	21% 11% 3 7% 4 3 3 4 4 6% 34%	1872
	21st to end	Night	19% 9% 3 7% 4 4 5% 4 4 6% 35%	1710
May	1st to 10th	Night	16% 8% 2 6% 4 4 4 3 5% 6% 42%	2633
	11th to 20th	Night	14% 4 1 4 4 2 4 3 5% 7% 51%	2506
	21st to end	Night	14% 8% 3 6% 4 4 4 4 5% 7% 41%	2743
June	1st to 10th	Night	10% 5% 2 7% 4 3 5% 4 5% 8% 49%	1520
	11th to 20th	Night	9% 5% 1 5% 5% 4 5% 5% 6% 7% 47%	1520
	21st to end	Night	7% 4 2 5% 4 4 4 4 6% 9% 51%	1520
July	1st to 10th	Night	11% 4 2 5% 4 4 4 4 7% 9% 47%	2530
	11th to 20th	Night	4 2 1 4 4 3 4 4 6% 8% 59%	2530
	21st to end	Night	6% 4 2 4 3 4 3 4 6% 7% 58%	2778
August	1st to 10th	Night	13% 5% 3 5% 4 4 4 3 5% 7% 47%	2836
	11th to 20th	Night	14% 5% 2 3 3 3 4 3 5% 9% 51%	2798
	21st to end	Night	10% 7% 2 7% 4 4 4 4 5% 6% 47%	3342
September	1st to 10th	Night	9% 4 2 5% 3 4 4 4 4 7% 54%	1900
	11th to 20th	Night	10% 4 2 4 3 4 4 4 5% 7% 53%	1914
	21st to end	Night	14% 6% 2 4 4 3 4 3 4 6% 52%	2170
October	1st to 10th	Night	14% 6% 2 6% 4 3 3 3 4 6% 49%	2280
	11th to 20th	Night	16% 10% 2 6% 3 3 4 3 4 7% 42%	2280
	21st to end	Night	19% 11% 3 6% 3 3 4 3 4 6% 38%	2539
November	1st to 10th	Night	14% 8% 3 7% 4 3 4 3 5% 6% 42%	2584
	11th to 20th	Night	13% 11% 5% 11% 5% 5% 4 4 4 5% 33%	2660
	21st to end	Night	14% 10% 3 9% 6% 4 4 3 4 7% 37%	2660
December	1st to 10th	Night	10% 12% 4 11% 8% 5% 5% 3 4 7% 30%	2660
	11th to 20th	Night	11% 14% 6% 12% 7% 6% 4 3 5% 5% 27%	3279
	21st to end	Night	23% 14% 6% 11% 5% 4 4 3 4 5% 22%	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	66% 5% 11% 16% 3	2528
	11th to 20th	Day	64% 6% 10% 15% 5%	2534
	21st to end	Day	61% 6% 13% 15% 4	3135
February	1st to 10th	Day	52% 6% 15% 18% 8% 1	1710
	11th to 20th	Day	50% 5% 13% 23% 8% 1	1673
	21st to end	Day	51% 7% 12% 19% 10% 1	1479
March	1st to 10th	Day	44% 6% 14% 24% 11% 1	3344
	11th to 20th	Day	43% 5% 12% 31% 9% 1	3480
	21st to end	Day	63% 5% 10% 17% 5%	3867
April	1st to 10th	Day	48% 6% 14% 21% 11% 1	2280
	11th to 20th	Day	53% 6% 10% 18% 12% 2	2254
	21st to end	Day	54% 6% 12% 19% 8% 1	2470
May	1st to 10th	Day	41% 7% 12% 25% 13% 2	4308
	11th to 20th	Day	37% 7% 12% 28% 14% 2	4403
	21st to end	Day	45% 8% 12% 24% 10% 1	4837
June	1st to 10th	Day	33% 8% 15% 30% 13% 2	2660
	11th to 20th	Day	42% 9% 14% 21% 14% 1	2660
	21st to end	Day	37% 10% 16% 26% 10% 2	2660
July	1st to 10th	Day	38% 10% 20% 22% 11% 1	4371
	11th to 20th	Day	22% 6% 17% 35% 18% 1	4365
	21st to end	Day	29% 9% 16% 28% 17% 1	4632
August	1st to 10th	Day	37% 7% 13% 29% 12% 2	4090
	11th to 20th	Day	35% 8% 13% 34% 10%	4080
	21st to end	Day	36% 7% 16% 27% 13% 1	4317
September	1st to 10th	Day	35% 6% 14% 31% 13%	2280
	11th to 20th	Day	35% 8% 17% 32% 9%	2263
	21st to end	Day	39% 6% 12% 32% 11%	1990
October	1st to 10th	Day	30% 3 9% 35% 22%	3160
	11th to 20th	Day	39% 6% 11% 28% 16% 1	3140
	21st to end	Day	43% 5% 15% 28% 9%	3371
November	1st to 10th	Day	49% 7% 13% 18% 12% 2	1613
	11th to 20th	Day	57% 6% 14% 15% 8%	1520
	21st to end	Day	48% 6% 18% 20% 6% 1	1520
December	1st to 10th	Day	59% 7% 16% 13% 5%	1520
	11th to 20th	Day	58% 5% 17% 15% 5%	1915
	21st to end	Day	70% 6% 9% 10% 5%	2783
January	1st to 10th	Night	60% 5% 11% 17% 5%	4428
	11th to 20th	Night	60% 6% 13% 15% 5%	4432
	21st to end	Night	63% 4 9% 19% 5% 1	4532
February	1st to 10th	Night	50% 6% 12% 22% 9% 1	2470
	11th to 20th	Night	44% 5% 16% 25% 8% 1	2404
	21st to end	Night	48% 6% 12% 22% 11% 1	1975
March	1st to 10th	Night	37% 6% 14% 26% 17% 1	3527
	11th to 20th	Night	40% 7% 11% 27% 15% 1	3480
	21st to end	Night	60% 4 8% 21% 7% 1	3763
April	1st to 10th	Night	47% 5% 10% 23% 14% 1	1900
	11th to 20th	Night	50% 5% 10% 19% 14% 3	1872
	21st to end	Night	48% 6% 9% 20% 14% 2	1710
May	1st to 10th	Night	41% 7% 11% 19% 21% 1	2660
	11th to 20th	Night	33% 5% 11% 27% 20% 4	2507
	21st to end	Night	40% 8% 11% 24% 16% 1	2751
June	1st to 10th	Night	32% 7% 14% 28% 18% 2	1520
	11th to 20th	Night	34% 8% 13% 23% 19% 2	1520
	21st to end	Night	28% 8% 16% 30% 16% 3	1520
July	1st to 10th	Night	31% 8% 20% 25% 13% 1	2490
	11th to 20th	Night	20% 7% 16% 36% 19% 2	2482
	21st to end	Night	24% 7% 16% 32% 19% 3	2690
August	1st to 10th	Night	36% 7% 11% 28% 14% 4	2826
	11th to 20th	Night	32% 6% 16% 31% 15% 1	2825
	21st to end	Night	36% 8% 16% 27% 12% 2	3342
September	1st to 10th	Night	30% 5% 14% 33% 17% 1	1900
	11th to 20th	Night	29% 7% 17% 31% 16%	1914
	21st to end	Night	34% 5% 12% 31% 16% 1	2170
October	1st to 10th	Night	24% 3 7% 36% 26% 4	3800
	11th to 20th	Night	33% 5% 13% 24% 21% 3	3779
	21st to end	Night	44% 5% 12% 27% 12%	4175
November	1st to 10th	Night	42% 6% 14% 23% 14% 1	2584
	11th to 20th	Night	53% 6% 13% 17% 10% 1	2660
	21st to end	Night	49% 5% 16% 22% 6% 1	2660
December	1st to 10th	Night	54% 6% 15% 19% 6%	2660
	11th to 20th	Night	58% 7% 13% 17% 5% 1	3281
	21st to end	Night	66% 4 12% 15% 3	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% 2	270
	11th to 20th	Day	16% 14% 39% 24% 6%	270
	21st to end	Day	16% 9% 42% 23% 8% 2	297
February	1st to 10th	Day	14% 15% 43% 22% 5% 1	270
	11th to 20th	Day	15% 17% 39% 23% 5% 1	270
	21st to end	Day	17% 14% 43% 24% 2	225
March	1st to 10th	Day	17% 15% 41% 21% 6%	270
	11th to 20th	Day	19% 16% 34% 23% 7% 1	270
	21st to end	Day	27% 15% 27% 20% 8% 2	325
April	1st to 10th	Day	22% 16% 35% 20% 6% 1	460
	11th to 20th	Day	31% 13% 25% 22% 9%	452
	21st to end	Day	27% 14% 30% 20% 8% 1	650
May	1st to 10th	Day	20% 16% 32% 23% 8% 1	653
	11th to 20th	Day	17% 15% 31% 23% 12% 3	675
	21st to end	Day	18% 11% 28% 25% 15% 3	734
June	1st to 10th	Day	9% 10% 30% 32% 15% 3	680
	11th to 20th	Day	13% 11% 38% 28% 9% 2	680
	21st to end	Day	12% 11% 32% 26% 15% 4	680
July	1st to 10th	Day	8% 6% 25% 32% 21% 8%	671
	11th to 20th	Day	10% 7% 29% 28% 20% 6%	668
	21st to end	Day	6% 5% 29% 35% 19% 6%	739
August	1st to 10th	Day	11% 5% 25% 35% 19% 5%	676
	11th to 20th	Day	14% 5% 23% 31% 23% 5%	665
	21st to end	Day	12% 7% 28% 32% 16% 5%	625
September	1st to 10th	Day	13% 9% 31% 27% 16% 3	490
	11th to 20th	Day	14% 7% 29% 30% 18% 2	473
	21st to end	Day	16% 17% 31% 20% 13% 3	300
October	1st to 10th	Day	19% 14% 27% 24% 12% 4	300
	11th to 20th	Day	17% 21% 39% 17% 6%	300
	21st to end	Day	24% 18% 39% 13% 5% 1	330
November	1st to 10th	Day	20% 18% 35% 19% 7% 1	285
	11th to 20th	Day	17% 22% 37% 20% 3	270
	21st to end	Day	22% 16% 42% 15% 4	270
December	1st to 10th	Day	14% 13% 39% 24% 8% 1	270
	11th to 20th	Day	19% 17% 33% 26% 5%	270
	21st to end	Day	29% 15% 36% 17% 2	297
January	1st to 10th	Night	11% 12% 37% 31% 8%	950
	11th to 20th	Night	16% 12% 37% 29% 5% 1	950
	21st to end	Night	17% 12% 37% 29% 5% 1	1045
February	1st to 10th	Night	13% 12% 40% 28% 7% 1	950
	11th to 20th	Night	12% 12% 41% 27% 7% 1	929
	21st to end	Night	17% 13% 33% 29% 8%	719
March	1st to 10th	Night	15% 11% 36% 29% 8%	644
	11th to 20th	Night	18% 11% 38% 27% 6%	570
	21st to end	Night	22% 13% 28% 25% 12% 1	627
April	1st to 10th	Night	23% 12% 34% 26% 5%	570
	11th to 20th	Night	25% 11% 32% 26% 6%	563
	21st to end	Night	22% 9% 34% 25% 8% 1	570
May	1st to 10th	Night	20% 11% 32% 29% 7% 1	570
	11th to 20th	Night	16% 9% 34% 30% 10% 1	561
	21st to end	Night	13% 9% 29% 35% 13%	617
June	1st to 10th	Night	10% 6% 31% 40% 12%	570
	11th to 20th	Night	10% 5% 34% 45% 7%	570
	21st to end	Night	9% 4 27% 42% 16% 2	570
July	1st to 10th	Night	6% 3 22% 40% 28% 2	555
	11th to 20th	Night	6% 4 29% 42% 18% 1	552
	21st to end	Night	5% 2 28% 44% 20% 2	624
August	1st to 10th	Night	8% 4 19% 49% 20% 1	567
	11th to 20th	Night	13% 4 19% 37% 26% 2	564
	21st to end	Night	7% 5% 28% 35% 22% 2	627
September	1st to 10th	Night	9% 8% 25% 38% 17% 3	570
	11th to 20th	Night	11% 7% 31% 32% 16% 2	570
	21st to end	Night	15% 9% 32% 29% 15% 1	650
October	1st to 10th	Night	17% 11% 29% 30% 13% 1	760
	11th to 20th	Night	21% 12% 33% 26% 8% 1	760
	21st to end	Night	24% 12% 30% 27% 7%	836
November	1st to 10th	Night	19% 12% 33% 29% 7% 1	865
	11th to 20th	Night	18% 15% 35% 25% 7%	950
	21st to end	Night	18% 15% 35% 25% 7%	950
December	1st to 10th	Night	16% 10% 37% 30% 6% 1	950
	11th to 20th	Night	20% 9% 39% 26% 6%	950
	21st to end	Night	24% 12% 35% 25% 4	1045

Page generated at 2024-11-03 12:18:59. Version ac07

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