Dauphin
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Dauphin 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	11% 9% 4 7% 7% 4 5% 5% 6% 7% 35%	82542
	Night	10% 10% 5% 9% 7% 4 5% 5% 5% 7% 35%	86243
Transparency	Day	47% 8% 14% 22% 9% 1	82252
	Night	49% 7% 13% 21% 9% 1	86114
Seeing	Day	16% 7% 28% 30% 16% 4	15369
	Night	16% 6% 26% 35% 15% 2	25550

By Month

Percentage Cloud Cover NW (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	5% 16% 6% 11% 9% 5% 9% 7% 6% 6% 20%	2219
	11th to 20th	Day	4 8% 6% 16% 14% 7% 8% 7% 6% 6% 19%	2324
	21st to end	Day	6% 14% 7% 9% 6% 4 6% 5% 5% 5% 33%	2794
February	1st to 10th	Day	9% 10% 4 10% 9% 6% 7% 7% 6% 6% 25%	1520
	11th to 20th	Day	6% 9% 5% 8% 9% 6% 8% 7% 7% 6% 28%	1627
	21st to end	Day	6% 9% 6% 9% 9% 5% 6% 8% 4 7% 31%	1570
March	1st to 10th	Day	9% 12% 5% 8% 8% 5% 6% 5% 5% 7% 30%	3130
	11th to 20th	Day	7% 11% 6% 10% 8% 4 5% 6% 6% 6% 30%	3377
	21st to end	Day	8% 8% 4 7% 8% 4 6% 5% 5% 7% 38%	3959
April	1st to 10th	Day	9% 10% 3 7% 6% 3 6% 5% 6% 7% 38%	2283
	11th to 20th	Day	12% 11% 5% 7% 7% 3 5% 5% 5% 7% 33%	2312
	21st to end	Day	12% 7% 2 7% 7% 3 6% 5% 6% 7% 38%	2340
May	1st to 10th	Day	16% 8% 4 6% 5% 4 5% 5% 6% 6% 35%	2474
	11th to 20th	Day	15% 8% 2 5% 5% 2 4 5% 5% 7% 41%	2645
	21st to end	Day	25% 7% 2 5% 5% 3 5% 5% 5% 7% 31%	2918
June	1st to 10th	Day	18% 6% 3 5% 5% 3 5% 5% 5% 7% 37%	2700
	11th to 20th	Day	18% 6% 3 7% 6% 4 5% 5% 6% 7% 32%	2700
	21st to end	Day	14% 5% 3 5% 6% 3 5% 5% 7% 9% 36%	2700
July	1st to 10th	Day	7% 4 2 5% 5% 3 5% 5% 7% 9% 48%	2700
	11th to 20th	Day	11% 5% 2 5% 5% 3 5% 5% 7% 9% 41%	2700
	21st to end	Day	8% 5% 2 4 4 4 5% 6% 7% 9% 48%	2823
August	1st to 10th	Day	9% 4 2 4 4 3 5% 6% 6% 8% 47%	2507
	11th to 20th	Day	12% 5% 2 4 4 2 5% 4 6% 8% 47%	2370
	21st to end	Day	15% 6% 2 5% 4 3 4 3 6% 7% 45%	2574
September	1st to 10th	Day	12% 5% 2 5% 5% 3 4 5% 5% 8% 46%	2198
	11th to 20th	Day	17% 6% 2 5% 5% 3 4 4 5% 8% 40%	2002
	21st to end	Day	14% 6% 3 6% 5% 2 5% 5% 5% 7% 43%	1980
October	1st to 10th	Day	17% 12% 4 6% 5% 3 4 4 4 7% 35%	1919
	11th to 20th	Day	15% 12% 3 6% 5% 3 4 5% 6% 7% 35%	1620
	21st to end	Day	14% 14% 6% 9% 6% 4 5% 5% 5% 7% 26%	1782
November	1st to 10th	Day	18% 17% 5% 8% 6% 4 3 4 3 4 28%	1597
	11th to 20th	Day	9% 13% 6% 13% 8% 3 5% 4 5% 6% 28%	1397
	21st to end	Day	11% 15% 6% 10% 8% 5% 5% 5% 4 6% 25%	1330
December	1st to 10th	Day	6% 11% 6% 12% 9% 5% 8% 5% 6% 7% 25%	1330
	11th to 20th	Day	11% 13% 7% 14% 11% 5% 6% 5% 5% 5% 20%	1679
	21st to end	Day	5% 9% 4 8% 7% 3 4 5% 6% 5% 44%	2442
January	1st to 10th	Night	5% 13% 9% 12% 9% 6% 6% 6% 6% 6% 23%	4737
	11th to 20th	Night	4 9% 6% 15% 14% 8% 10% 7% 5% 4 17%	4582
	21st to end	Night	6% 13% 8% 12% 8% 4 6% 5% 5% 6% 29%	4873
February	1st to 10th	Night	9% 10% 5% 10% 7% 5% 8% 7% 4 5% 28%	2660
	11th to 20th	Night	5% 8% 4 8% 8% 6% 8% 6% 7% 7% 33%	2455
	21st to end	Night	6% 8% 6% 11% 9% 5% 6% 5% 4 6% 33%	1884
March	1st to 10th	Night	8% 13% 4 9% 8% 4 5% 5% 6% 8% 31%	3734
	11th to 20th	Night	8% 13% 5% 7% 8% 3 4 4 4 7% 38%	3583
	21st to end	Night	8% 9% 4 8% 8% 4 6% 5% 6% 6% 37%	3673
April	1st to 10th	Night	7% 8% 4 7% 7% 3 5% 5% 6% 8% 39%	1886
	11th to 20th	Night	15% 9% 5% 7% 5% 4 5% 5% 5% 6% 34%	1599
	21st to end	Night	12% 10% 3 7% 5% 4 5% 5% 6% 7% 35%	1620
May	1st to 10th	Night	16% 8% 3 6% 6% 3 5% 5% 5% 7% 36%	1483
	11th to 20th	Night	14% 8% 3 5% 4 3 3 4 5% 9% 43%	1249
	21st to end	Night	23% 5% 3 5% 5% 2 4 4 5% 7% 39%	1358
June	1st to 10th	Night	19% 7% 3 5% 5% 2 4 4 5% 7% 39%	1260
	11th to 20th	Night	17% 5% 3 5% 4 3 5% 5% 6% 8% 39%	1260
	21st to end	Night	12% 5% 2 5% 5% 3 6% 8% 7% 8% 38%	1260
July	1st to 10th	Night	7% 4 2 3 3 3 4 3 7% 8% 55%	1260
	11th to 20th	Night	8% 3 1 4 4 4 6% 5% 6% 9% 50%	1260
	21st to end	Night	7% 4 2 5% 4 3 4 4 7% 10% 51%	1491
August	1st to 10th	Night	9% 3 2 3 4 3 4 6% 5% 8% 52%	1432
	11th to 20th	Night	9% 4 2 4 4 3 3 4 5% 10% 52%	1531
	21st to end	Night	15% 5% 1 4 3 2 3 4 5% 9% 49%	1782
September	1st to 10th	Night	9% 4 2 4 4 3 5% 4 6% 7% 51%	1759
	11th to 20th	Night	15% 6% 3 5% 4 2 4 3 5% 6% 46%	1957
	21st to end	Night	13% 7% 3 5% 6% 3 4 5% 6% 7% 43%	1980
October	1st to 10th	Night	17% 8% 2 6% 5% 2 4 4 5% 7% 40%	2020
	11th to 20th	Night	14% 11% 3 6% 6% 3 4 5% 5% 7% 36%	2340
	21st to end	Night	13% 13% 4 7% 6% 3 5% 5% 5% 6% 32%	2574
November	1st to 10th	Night	15% 15% 5% 10% 6% 3 5% 4 4 5% 28%	2479
	11th to 20th	Night	9% 16% 6% 12% 9% 4 4 4 4 5% 27%	2779
	21st to end	Night	11% 14% 7% 12% 8% 3 5% 5% 4 5% 27%	2850
December	1st to 10th	Night	7% 12% 6% 12% 8% 5% 7% 5% 5% 7% 27%	2850
	11th to 20th	Night	8% 15% 7% 12% 8% 4 5% 5% 4 6% 25%	3518
	21st to end	Night	6% 9% 4 9% 7% 3 4 5% 6% 7% 39%	5225

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	60% 10% 14% 13% 3	2219
	11th to 20th	Day	65% 6% 9% 17% 3	2346
	21st to end	Day	52% 7% 9% 26% 5%	2794
February	1st to 10th	Day	55% 9% 14% 14% 8%	1520
	11th to 20th	Day	52% 8% 13% 18% 10%	1636
	21st to end	Day	52% 6% 12% 20% 10%	1570
March	1st to 10th	Day	52% 7% 13% 21% 7%	3130
	11th to 20th	Day	51% 10% 14% 17% 7%	3379
	21st to end	Day	43% 9% 14% 21% 13%	3959
April	1st to 10th	Day	43% 9% 14% 21% 12% 1	2283
	11th to 20th	Day	52% 7% 11% 18% 11% 1	2312
	21st to end	Day	44% 10% 14% 22% 9% 1	2340
May	1st to 10th	Day	48% 7% 11% 23% 11% 1	2474
	11th to 20th	Day	42% 7% 13% 23% 13% 2	2649
	21st to end	Day	52% 8% 9% 18% 12% 1	2918
June	1st to 10th	Day	45% 10% 14% 22% 8% 1	2700
	11th to 20th	Day	48% 10% 16% 16% 9% 1	2700
	21st to end	Day	42% 10% 18% 23% 5% 1	2700
July	1st to 10th	Day	30% 11% 20% 29% 10% 1	2626
	11th to 20th	Day	36% 11% 17% 27% 9%	2619
	21st to end	Day	31% 10% 19% 33% 7%	2666
August	1st to 10th	Day	32% 13% 18% 28% 9% 1	2491
	11th to 20th	Day	35% 8% 20% 29% 7%	2370
	21st to end	Day	37% 8% 17% 29% 8%	2574
September	1st to 10th	Day	36% 9% 15% 27% 12% 1	2198
	11th to 20th	Day	43% 8% 16% 24% 9%	2002
	21st to end	Day	41% 8% 14% 27% 10%	1980
October	1st to 10th	Day	51% 6% 16% 21% 6%	1919
	11th to 20th	Day	48% 9% 12% 25% 6% 1	1620
	21st to end	Day	59% 8% 12% 15% 6%	1782
November	1st to 10th	Day	62% 5% 10% 17% 6% 1	1597
	11th to 20th	Day	57% 8% 14% 14% 6% 1	1397
	21st to end	Day	61% 7% 10% 18% 4	1330
December	1st to 10th	Day	57% 9% 13% 15% 6%	1330
	11th to 20th	Day	63% 8% 11% 14% 4	1680
	21st to end	Day	39% 6% 16% 18% 17% 4	2442
January	1st to 10th	Night	59% 9% 10% 16% 6%	4737
	11th to 20th	Night	69% 6% 8% 13% 4	4622
	21st to end	Night	55% 8% 14% 17% 6%	4873
February	1st to 10th	Night	55% 7% 11% 17% 8% 1	2660
	11th to 20th	Night	47% 8% 13% 21% 11% 1	2456
	21st to end	Night	51% 5% 11% 24% 9%	1884
March	1st to 10th	Night	50% 8% 11% 24% 7%	3734
	11th to 20th	Night	45% 6% 13% 20% 15% 1	3583
	21st to end	Night	44% 9% 10% 29% 8%	3673
April	1st to 10th	Night	41% 7% 13% 19% 17% 2	1886
	11th to 20th	Night	50% 6% 9% 20% 12% 3	1599
	21st to end	Night	46% 8% 13% 21% 10% 2	1620
May	1st to 10th	Night	48% 8% 9% 19% 15% 1	1483
	11th to 20th	Night	41% 5% 10% 25% 17% 2	1249
	21st to end	Night	45% 7% 12% 21% 15% 1	1358
June	1st to 10th	Night	46% 7% 13% 22% 10% 1	1260
	11th to 20th	Night	43% 8% 14% 21% 12% 2	1260
	21st to end	Night	39% 14% 18% 23% 6% 1	1260
July	1st to 10th	Night	27% 7% 19% 35% 12% 1	1225
	11th to 20th	Night	29% 10% 20% 31% 10% 1	1218
	21st to end	Night	28% 9% 18% 33% 10% 1	1408
August	1st to 10th	Night	29% 8% 20% 32% 11%	1424
	11th to 20th	Night	29% 8% 20% 33% 8% 1	1531
	21st to end	Night	32% 8% 14% 32% 13%	1782
September	1st to 10th	Night	30% 8% 16% 29% 14% 2	1759
	11th to 20th	Night	39% 7% 13% 29% 10% 1	1957
	21st to end	Night	40% 8% 11% 30% 10% 1	1980
October	1st to 10th	Night	45% 7% 15% 23% 8% 1	2020
	11th to 20th	Night	47% 7% 11% 26% 8%	2340
	21st to end	Night	52% 7% 13% 22% 5%	2574
November	1st to 10th	Night	59% 7% 12% 15% 6% 2	2479
	11th to 20th	Night	61% 8% 12% 14% 4	2779
	21st to end	Night	59% 7% 14% 14% 5%	2850
December	1st to 10th	Night	56% 6% 14% 15% 7%	2850
	11th to 20th	Night	58% 8% 13% 15% 5% 1	3516
	21st to end	Night	44% 6% 13% 17% 15% 5%	5225

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	13% 6% 29% 33% 15% 4	270
	11th to 20th	Day	11% 6% 29% 41% 11% 3	270
	21st to end	Day	16% 6% 27% 31% 17% 2	297
February	1st to 10th	Day	14% 4 32% 35% 13% 1	270
	11th to 20th	Day	11% 6% 32% 29% 18% 4	270
	21st to end	Day	7% 8% 32% 32% 18% 3	225
March	1st to 10th	Day	17% 6% 22% 37% 16% 2	270
	11th to 20th	Day	15% 9% 29% 31% 13% 3	270
	21st to end	Day	17% 7% 29% 28% 17% 3	378
April	1st to 10th	Day	13% 10% 34% 28% 11% 3	471
	11th to 20th	Day	19% 7% 30% 30% 12% 2	590
	21st to end	Day	16% 9% 28% 34% 12% 2	600
May	1st to 10th	Day	15% 6% 30% 29% 19% 1	603
	11th to 20th	Day	19% 6% 29% 28% 15% 3	625
	21st to end	Day	23% 6% 22% 27% 18% 3	679
June	1st to 10th	Day	19% 9% 29% 24% 13% 6%	630
	11th to 20th	Day	20% 10% 26% 25% 13% 6%	630
	21st to end	Day	15% 5% 22% 36% 17% 5%	630
July	1st to 10th	Day	11% 6% 24% 32% 20% 7%	621
	11th to 20th	Day	11% 5% 29% 31% 19% 4	618
	21st to end	Day	10% 6% 25% 32% 20% 7%	684
August	1st to 10th	Day	10% 5% 27% 31% 19% 8%	626
	11th to 20th	Day	12% 5% 21% 30% 22% 10%	615
	21st to end	Day	17% 4 22% 33% 22% 3	693
September	1st to 10th	Day	13% 8% 35% 28% 14% 2	488
	11th to 20th	Day	16% 9% 28% 29% 16% 2	292
	21st to end	Day	17% 6% 31% 30% 13% 3	270
October	1st to 10th	Day	26% 7% 27% 23% 14% 3	270
	11th to 20th	Day	21% 4 35% 23% 14% 3	270
	21st to end	Day	23% 9% 28% 30% 6% 4	297
November	1st to 10th	Day	27% 10% 27% 25% 9% 2	270
	11th to 20th	Day	16% 9% 33% 28% 10% 3	270
	21st to end	Day	22% 11% 33% 24% 9% 1	270
December	1st to 10th	Day	12% 10% 28% 32% 15% 3	270
	11th to 20th	Day	14% 6% 39% 31% 9% 2	270
	21st to end	Day	13% 5% 26% 32% 21% 4	297
January	1st to 10th	Night	13% 8% 30% 37% 11% 2	950
	11th to 20th	Night	15% 6% 31% 33% 13% 2	950
	21st to end	Night	15% 5% 33% 35% 11% 1	1045
February	1st to 10th	Night	15% 5% 28% 36% 15% 2	950
	11th to 20th	Night	9% 6% 28% 39% 16% 2	925
	21st to end	Night	10% 4 25% 39% 19% 3	628
March	1st to 10th	Night	16% 5% 24% 37% 16% 2	760
	11th to 20th	Night	12% 8% 27% 36% 15% 2	634
	21st to end	Night	18% 4 26% 34% 15% 3	627
April	1st to 10th	Night	11% 7% 23% 42% 15% 1	570
	11th to 20th	Night	19% 5% 26% 35% 14%	533
	21st to end	Night	16% 6% 27% 36% 14%	540
May	1st to 10th	Night	19% 5% 23% 38% 14% 1	540
	11th to 20th	Night	17% 8% 23% 33% 18% 1	531
	21st to end	Night	24% 5% 16% 38% 15% 1	584
June	1st to 10th	Night	20% 4 25% 33% 16% 2	540
	11th to 20th	Night	19% 3 25% 36% 16% 2	540
	21st to end	Night	13% 3 23% 40% 20%	540
July	1st to 10th	Night	9% 3 22% 44% 22% 1	525
	11th to 20th	Night	10% 4 25% 41% 19% 2	522
	21st to end	Night	9% 3 19% 42% 22% 4	591
August	1st to 10th	Night	11% 4 21% 41% 21% 2	537
	11th to 20th	Night	10% 3 18% 37% 28% 4	534
	21st to end	Night	16% 4 21% 37% 20% 1	594
September	1st to 10th	Night	12% 5% 23% 39% 19% 2	540
	11th to 20th	Night	18% 6% 22% 41% 12% 1	540
	21st to end	Night	15% 5% 29% 37% 13% 2	540
October	1st to 10th	Night	23% 4 25% 36% 12% 1	580
	11th to 20th	Night	21% 7% 25% 32% 14% 1	900
	21st to end	Night	19% 9% 29% 31% 10% 1	990
November	1st to 10th	Night	24% 8% 30% 27% 11% 1	925
	11th to 20th	Night	16% 7% 35% 30% 9% 2	950
	21st to end	Night	18% 8% 34% 31% 8% 1	950
December	1st to 10th	Night	13% 8% 28% 33% 15% 3	950
	11th to 20th	Night	17% 7% 31% 30% 13% 2	950
	21st to end	Night	15% 6% 25% 34% 17% 2	1045

Page generated at 2024-04-07 08:28:13. Version ac07

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