Melfort
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Melfort clear sky chart from 2005-11-06 to 2026-07-31.

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	10% 9% 3 8% 5% 5% 5% 4 6% 8% 37%	142242
	Night	8% 9% 4 10% 6% 5% 5% 4 6% 7% 34%	139485
Transparency	Day	45% 5% 16% 25% 9% 1	141939
	Night	48% 4 15% 24% 9% 1	139372
Seeing	Day	15% 7% 27% 30% 17% 5%	18283
	Night	14% 6% 29% 35% 14% 2	27512

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% 14% 6% 17% 9% 8% 6% 4 6% 8% 17%	3563
	11th to 20th	Day	5% 9% 3 12% 11% 9% 6% 6% 7% 7% 25%	4119
	21st to end	Day	5% 12% 5% 12% 7% 6% 5% 4 6% 9% 29%	5086
February	1st to 10th	Day	7% 11% 4 13% 7% 6% 7% 6% 8% 8% 21%	1680
	11th to 20th	Day	6% 11% 4 10% 6% 6% 8% 6% 7% 7% 30%	1817
	21st to end	Day	4 12% 6% 15% 10% 6% 5% 4 6% 7% 26%	1653
March	1st to 10th	Day	7% 14% 6% 13% 8% 8% 6% 4 6% 6% 21%	4600
	11th to 20th	Day	7% 12% 5% 12% 6% 6% 5% 4 5% 7% 31%	4827
	21st to end	Day	9% 11% 4 8% 4 4 4 4 6% 6% 40%	6050
April	1st to 10th	Day	6% 11% 3 7% 5% 4 5% 4 5% 8% 41%	2520
	11th to 20th	Day	12% 13% 4 10% 6% 4 4 4 6% 8% 31%	2598
	21st to end	Day	11% 9% 4 9% 5% 5% 5% 4 5% 9% 33%	2940
May	1st to 10th	Day	9% 10% 3 7% 4 4 5% 4 6% 7% 42%	8224
	11th to 20th	Day	14% 9% 3 9% 6% 5% 5% 4 5% 7% 32%	8324
	21st to end	Day	12% 7% 2 6% 4 4 4 3 5% 8% 44%	10000
June	1st to 10th	Day	17% 7% 3 7% 6% 5% 6% 4 7% 7% 31%	3360
	11th to 20th	Day	22% 8% 3 7% 5% 5% 6% 4 6% 6% 27%	3360
	21st to end	Day	16% 7% 2 6% 5% 5% 5% 4 6% 9% 35%	3360
July	1st to 10th	Day	8% 4 2 5% 3 4 4 4 6% 9% 51%	7400
	11th to 20th	Day	10% 5% 2 5% 4 4 5% 3 6% 9% 47%	7242
	21st to end	Day	8% 4 1 5% 3 4 5% 4 7% 10% 50%	7220
August	1st to 10th	Day	12% 4 2 5% 4 4 5% 4 7% 10% 43%	4552
	11th to 20th	Day	9% 5% 2 7% 5% 5% 5% 4 5% 8% 46%	4483
	21st to end	Day	13% 5% 2 6% 3 4 4 3 5% 7% 47%	4569
September	1st to 10th	Day	11% 5% 3 7% 5% 5% 5% 4 5% 7% 43%	2400
	11th to 20th	Day	13% 7% 3 6% 4 5% 5% 4 5% 8% 39%	2388
	21st to end	Day	10% 6% 2 6% 4 4 3 3 5% 7% 49%	2165
October	1st to 10th	Day	13% 9% 2 5% 4 3 4 3 5% 7% 45%	3270
	11th to 20th	Day	8% 7% 3 8% 5% 4 6% 4 7% 11% 37%	3037
	21st to end	Day	8% 14% 5% 9% 5% 6% 6% 4 6% 6% 31%	3190
November	1st to 10th	Day	15% 17% 5% 10% 6% 4 4 3 5% 6% 24%	1654
	11th to 20th	Day	9% 16% 6% 14% 8% 6% 5% 4 4 5% 23%	1549
	21st to end	Day	8% 15% 6% 13% 8% 5% 5% 4 6% 6% 24%	1470
December	1st to 10th	Day	9% 14% 6% 14% 9% 7% 5% 4 5% 5% 22%	2195
	11th to 20th	Day	6% 12% 6% 16% 9% 7% 6% 4 5% 7% 24%	2319
	21st to end	Day	3 10% 6% 13% 8% 5% 5% 4 5% 5% 35%	3058
January	1st to 10th	Night	5% 12% 6% 17% 9% 7% 6% 4 6% 7% 21%	9329
	11th to 20th	Night	4 10% 5% 14% 10% 8% 8% 6% 8% 8% 21%	8779
	21st to end	Night	5% 10% 5% 13% 7% 6% 6% 6% 7% 7% 28%	9110
February	1st to 10th	Night	8% 11% 5% 10% 8% 7% 7% 5% 6% 8% 25%	2940
	11th to 20th	Night	4 10% 4 11% 7% 7% 7% 5% 6% 7% 32%	2709
	21st to end	Night	4 9% 4 9% 8% 6% 7% 5% 7% 8% 32%	2153
March	1st to 10th	Night	7% 11% 6% 12% 7% 6% 6% 5% 7% 8% 25%	5494
	11th to 20th	Night	7% 10% 4 12% 7% 6% 5% 5% 6% 9% 28%	5366
	21st to end	Night	7% 10% 4 8% 5% 5% 5% 4 6% 8% 38%	5146
April	1st to 10th	Night	6% 10% 3 7% 5% 4 5% 4 7% 9% 40%	2100
	11th to 20th	Night	13% 10% 3 7% 6% 5% 4 4 7% 7% 35%	1971
	21st to end	Night	14% 8% 3 7% 6% 5% 5% 4 6% 8% 34%	1680
May	1st to 10th	Night	11% 8% 3 6% 4 4 4 3 5% 7% 43%	4724
	11th to 20th	Night	15% 9% 4 9% 5% 6% 5% 4 6% 7% 29%	4566
	21st to end	Night	13% 8% 2 6% 4 4 4 3 5% 8% 43%	4173
June	1st to 10th	Night	14% 7% 2 5% 4 3 4 4 7% 10% 42%	1260
	11th to 20th	Night	16% 8% 3 7% 5% 6% 4 4 6% 7% 34%	1260
	21st to end	Night	16% 6% 1 5% 3 4 5% 3 7% 9% 40%	1260
July	1st to 10th	Night	8% 4 2 5% 4 4 6% 5% 7% 9% 47%	2780
	11th to 20th	Night	10% 4 2 4 3 3 4 4 6% 8% 54%	2935
	21st to end	Night	6% 3 2 5% 3 3 4 3 5% 8% 57%	3856
August	1st to 10th	Night	9% 4 2 5% 3 3 4 4 6% 9% 51%	2608
	11th to 20th	Night	9% 4 1 5% 4 3 4 4 7% 10% 48%	2576
	21st to end	Night	10% 4 1 4 3 3 4 3 6% 8% 52%	3337
September	1st to 10th	Night	10% 6% 2 5% 4 4 4 4 5% 8% 49%	2000
	11th to 20th	Night	14% 6% 2 5% 4 3 4 4 5% 7% 44%	2012
	21st to end	Night	9% 6% 2 5% 4 3 4 4 6% 8% 50%	2233
October	1st to 10th	Night	10% 8% 2 5% 4 4 4 3 5% 8% 47%	3920
	11th to 20th	Night	8% 7% 3 7% 5% 5% 5% 4 5% 7% 44%	4078
	21st to end	Night	11% 11% 4 9% 4 4 4 4 5% 8% 36%	4610
November	1st to 10th	Night	15% 17% 4 10% 6% 4 5% 3 5% 6% 24%	2860
	11th to 20th	Night	8% 15% 7% 14% 7% 5% 4 4 6% 6% 25%	3071
	21st to end	Night	6% 14% 5% 13% 7% 7% 6% 4 6% 7% 25%	3150
December	1st to 10th	Night	7% 16% 7% 16% 10% 8% 6% 4 4 5% 18%	5206
	11th to 20th	Night	5% 11% 6% 13% 7% 7% 6% 5% 6% 8% 25%	6093
	21st to end	Night	4 10% 5% 15% 7% 5% 4 3 5% 5% 38%	8140

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	65% 4 10% 14% 7%	3563
	11th to 20th	Day	55% 5% 13% 22% 5%	4140
	21st to end	Day	53% 4 19% 16% 8%	5086
February	1st to 10th	Day	57% 5% 14% 16% 8%	1680
	11th to 20th	Day	51% 4 12% 23% 10%	1826
	21st to end	Day	58% 3 11% 19% 8%	1653
March	1st to 10th	Day	61% 4 14% 15% 6%	4600
	11th to 20th	Day	52% 5% 13% 21% 10%	4828
	21st to end	Day	44% 4 8% 26% 16% 1	6050
April	1st to 10th	Day	41% 5% 16% 24% 13%	2520
	11th to 20th	Day	53% 4 13% 20% 9% 1	2598
	21st to end	Day	48% 4 15% 24% 8% 1	2940
May	1st to 10th	Day	40% 4 10% 32% 13% 1	8224
	11th to 20th	Day	50% 5% 10% 25% 9% 1	8328
	21st to end	Day	39% 5% 11% 27% 18% 1	10000
June	1st to 10th	Day	49% 6% 13% 21% 10% 1	3360
	11th to 20th	Day	55% 6% 14% 18% 7% 1	3360
	21st to end	Day	45% 6% 18% 23% 7%	3360
July	1st to 10th	Day	29% 5% 30% 32% 5%	7321
	11th to 20th	Day	33% 5% 18% 40% 3	7155
	21st to end	Day	30% 5% 25% 33% 7%	7022
August	1st to 10th	Day	35% 6% 27% 28% 4	4536
	11th to 20th	Day	37% 5% 22% 29% 7%	4525
	21st to end	Day	37% 4 22% 31% 5%	4568
September	1st to 10th	Day	39% 5% 18% 26% 10% 2	2400
	11th to 20th	Day	43% 5% 20% 26% 6%	2388
	21st to end	Day	35% 4 16% 31% 12% 1	2165
October	1st to 10th	Day	40% 3 20% 28% 9%	3270
	11th to 20th	Day	41% 4 21% 27% 6%	3037
	21st to end	Day	52% 4 20% 21% 3	3190
November	1st to 10th	Day	61% 4 12% 17% 5%	1654
	11th to 20th	Day	64% 4 14% 14% 4	1549
	21st to end	Day	60% 5% 14% 17% 5%	1470
December	1st to 10th	Day	64% 5% 10% 16% 4 1	2195
	11th to 20th	Day	61% 3 15% 17% 4	2320
	21st to end	Day	51% 4 10% 20% 12% 3	3058
January	1st to 10th	Night	62% 3 10% 18% 6%	9330
	11th to 20th	Night	58% 5% 13% 17% 7%	8820
	21st to end	Night	53% 6% 17% 19% 6%	9110
February	1st to 10th	Night	55% 5% 13% 18% 9%	2940
	11th to 20th	Night	50% 4 12% 23% 10%	2710
	21st to end	Night	48% 5% 14% 22% 11%	2153
March	1st to 10th	Night	54% 5% 17% 18% 5% 1	5494
	11th to 20th	Night	50% 6% 13% 21% 10%	5366
	21st to end	Night	43% 4 9% 25% 17% 2	5146
April	1st to 10th	Night	39% 4 13% 27% 15% 2	2100
	11th to 20th	Night	47% 5% 12% 20% 14% 3	1971
	21st to end	Night	47% 4 13% 25% 10% 1	1680
May	1st to 10th	Night	40% 4 11% 28% 16% 2	4724
	11th to 20th	Night	53% 4 9% 23% 9% 1	4566
	21st to end	Night	40% 5% 8% 27% 21% 1	4176
June	1st to 10th	Night	37% 5% 18% 26% 13% 1	1260
	11th to 20th	Night	47% 7% 17% 18% 11% 1	1260
	21st to end	Night	39% 6% 20% 23% 9% 1	1260
July	1st to 10th	Night	33% 6% 23% 32% 6%	2750
	11th to 20th	Night	28% 4 16% 46% 6%	2899
	21st to end	Night	25% 4 27% 36% 7%	3749
August	1st to 10th	Night	30% 5% 24% 33% 8%	2600
	11th to 20th	Night	31% 5% 19% 38% 7%	2600
	21st to end	Night	29% 5% 22% 34% 9%	3337
September	1st to 10th	Night	34% 3 18% 30% 12% 2	2000
	11th to 20th	Night	39% 4 18% 31% 9%	2012
	21st to end	Night	31% 4 16% 31% 16% 1	2233
October	1st to 10th	Night	36% 3 19% 32% 10%	3920
	11th to 20th	Night	39% 4 15% 32% 10%	4078
	21st to end	Night	48% 4 19% 24% 6%	4610
November	1st to 10th	Night	60% 4 13% 16% 6% 1	2860
	11th to 20th	Night	60% 4 16% 15% 4	3071
	21st to end	Night	57% 6% 15% 17% 4	3150
December	1st to 10th	Night	70% 5% 8% 13% 4	5206
	11th to 20th	Night	56% 4 15% 20% 5%	6091
	21st to end	Night	49% 3 10% 22% 13% 2	8140

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	12% 6% 34% 23% 21% 4	220
	11th to 20th	Day	14% 7% 33% 31% 13% 2	220
	21st to end	Day	16% 8% 27% 31% 16% 2	344
February	1st to 10th	Day	11% 10% 31% 31% 14% 2	330
	11th to 20th	Day	10% 4 28% 34% 20% 5%	330
	21st to end	Day	7% 7% 33% 33% 16% 4	273
March	1st to 10th	Day	13% 5% 31% 32% 17% 2	330
	11th to 20th	Day	12% 8% 30% 32% 16% 3	414
	21st to end	Day	15% 5% 30% 31% 15% 4	594
April	1st to 10th	Day	11% 9% 34% 29% 12% 5%	540
	11th to 20th	Day	17% 10% 29% 28% 13% 3	612
	21st to end	Day	14% 7% 29% 31% 16% 3	750
May	1st to 10th	Day	13% 7% 26% 32% 17% 5%	753
	11th to 20th	Day	13% 8% 28% 26% 18% 6%	775
	21st to end	Day	18% 5% 23% 26% 23% 4	844
June	1st to 10th	Day	19% 9% 27% 26% 14% 4	780
	11th to 20th	Day	23% 9% 25% 25% 15% 4	780
	21st to end	Day	20% 5% 21% 27% 19% 8%	780
July	1st to 10th	Day	11% 5% 21% 32% 24% 7%	771
	11th to 20th	Day	13% 7% 21% 32% 20% 8%	768
	21st to end	Day	10% 4 23% 31% 23% 9%	845
August	1st to 10th	Day	13% 5% 19% 29% 26% 9%	726
	11th to 20th	Day	10% 5% 23% 32% 22% 8%	715
	21st to end	Day	14% 7% 24% 34% 16% 5%	658
September	1st to 10th	Day	15% 11% 27% 27% 17% 3	530
	11th to 20th	Day	18% 5% 29% 30% 15% 3	518
	21st to end	Day	12% 11% 28% 32% 15% 2	330
October	1st to 10th	Day	19% 8% 27% 27% 16% 3	330
	11th to 20th	Day	14% 11% 33% 27% 12% 4	330
	21st to end	Day	19% 10% 29% 26% 13% 1	363
November	1st to 10th	Day	22% 7% 29% 29% 9% 3	330
	11th to 20th	Day	18% 8% 38% 29% 6% 1	330
	21st to end	Day	14% 8% 37% 30% 9% 3	330
December	1st to 10th	Day	8% 9% 36% 32% 12% 3	278
	11th to 20th	Day	14% 9% 35% 35% 7%	220
	21st to end	Day	8% 3 30% 34% 19% 6%	242
January	1st to 10th	Night	13% 6% 32% 35% 13% 2	1050
	11th to 20th	Night	12% 7% 37% 32% 10% 1	1050
	21st to end	Night	14% 7% 36% 32% 10% 1	1155
February	1st to 10th	Night	12% 4 31% 36% 14% 2	1050
	11th to 20th	Night	9% 5% 29% 36% 17% 3	871
	21st to end	Night	8% 5% 26% 38% 19% 3	692
March	1st to 10th	Night	15% 5% 28% 36% 14% 2	840
	11th to 20th	Night	14% 5% 33% 35% 12% 1	840
	21st to end	Night	12% 3 30% 35% 17% 3	719
April	1st to 10th	Night	10% 5% 29% 38% 14% 3	630
	11th to 20th	Night	17% 6% 30% 32% 13% 2	623
	21st to end	Night	17% 6% 27% 37% 11% 1	630
May	1st to 10th	Night	15% 4 30% 36% 13% 1	630
	11th to 20th	Night	15% 5% 28% 34% 16% 1	621
	21st to end	Night	18% 5% 23% 38% 15% 1	567
June	1st to 10th	Night	18% 7% 28% 31% 15% 2	420
	11th to 20th	Night	20% 5% 23% 34% 15% 2	420
	21st to end	Night	18% 4 18% 39% 19% 1	420
July	1st to 10th	Night	9% 4 20% 42% 24% 1	410
	11th to 20th	Night	15% 3 20% 38% 22% 2	408
	21st to end	Night	9% 4 22% 40% 21% 4	599
August	1st to 10th	Night	9% 4 21% 36% 26% 4	597
	11th to 20th	Night	12% 2 20% 37% 25% 3	594
	21st to end	Night	15% 4 23% 38% 18% 2	660
September	1st to 10th	Night	14% 3 24% 37% 19% 3	600
	11th to 20th	Night	18% 4 23% 39% 16% 1	600
	21st to end	Night	11% 6% 34% 39% 10% 1	633
October	1st to 10th	Night	19% 4 29% 36% 11% 1	800
	11th to 20th	Night	15% 7% 30% 34% 13% 2	903
	21st to end	Night	19% 7% 31% 31% 11% 1	1100
November	1st to 10th	Night	24% 5% 31% 30% 8% 2	1025
	11th to 20th	Night	14% 9% 35% 29% 11% 2	1050
	21st to end	Night	14% 8% 35% 32% 10% 1	1050
December	1st to 10th	Night	11% 7% 33% 32% 14% 3	1050
	11th to 20th	Night	13% 8% 34% 32% 12% 2	1050
	21st to end	Night	12% 5% 27% 35% 18% 3	1155

Page generated at 2026-07-28 01:25:22. Version ac07

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